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Describe graphs qualitatively

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5331778
The graph shows a hike. The horizontal axis gives time \(t\) in hours, and the vertical axis gives distance \(s\) from the starting point in miles. a) For each section \(A\), \(B\), and \(C\), state whether the graph's slope is positive, negative, or zero. b) What does a negative slope mean in this context?
Figure for problem 533177

Hints

- Decide whether distance rises, stays constant, or falls in each section. - A downward graph segment means the distance from the starting point is decreasing.

Solution

1. In section \(A\), distance increases as time increases, so the slope is positive. In section \(B\), distance remains constant at \(5\) miles, so the slope is zero. In section \(C\), distance decreases as time increases, so the slope is negative. 2. A negative slope means the hiker's distance from the starting point is decreasing. The hiker is traveling back toward the starting point.

Answer

a) \(A\): positive; \(B\): zero; \(C\): negative b) The hiker is moving back toward the starting point.
5338858
The graph shows a hiking group’s elevation during a day hike. Decide whether each statement is **true** or **false**. Briefly explain your decision using the graph. 1. The hike began at an elevation of \(400\,\text{ft}\). 2. From hour \(3\) to hour \(4\), the group’s elevation stayed the same. 3. The highest point of the hike was at an elevation of \(1200\,\text{ft}\).
Figure for problem 533885

Hints

- Read the axis labels before checking each statement. - A horizontal part of the graph means the elevation does not change. - Find the greatest vertical value to identify the highest point.

Solution

1. At hour \(0\), the graph shows \(400\,\text{ft}\), so statement 1 is true. 2. From hour \(3\) to hour \(4\), the graph is horizontal at \(1000\,\text{ft}\), so statement 2 is true. 3. The greatest elevation is \(1400\,\text{ft}\) at hour \(5\), so statement 3 is false.

Answer

1. **True:** The graph begins at \(400\,\text{ft}\). 2. **True:** The elevation remains \(1000\,\text{ft}\) from hour \(3\) to hour \(4\). 3. **False:** The highest point is \(1400\,\text{ft}\).
5349048
The graph shows the growth of a sunflower over \(10\) weeks. 1. How tall is the sunflower after \(4\) weeks? 2. After how many weeks does the sunflower reach a height of \(150\,\text{cm}\)?
Figure for problem 534904

Hints

- Use the horizontal axis to locate the time and the vertical axis to read the height. - For question 2, start at \(150\,\text{cm}\) on the vertical axis and find the matching time on the graph.

Solution

1. At week \(4\), the graph has a height of \(75\,\text{cm}\). 2. The graph reaches \(150\,\text{cm}\) at week \(6\).

Answer

1. \(75\,\text{cm}\) 2. \(6\) weeks
5119168
A funnel-shaped container is narrow at the bottom and wide at the top. Water flows into it at a constant volume per second. a) Describe how the rate at which the water height rises changes over time. Explain using the shape of the container. b) Describe the graph of water height versus time. Does the graph become steeper or less steep? c) Suppose the container narrows again near the top, like a vase. How would the graph change in that region?

Hints

- Think about how much horizontal space the water has at each height. - A steeper graph represents a faster increase in water height. - For equal volumes of water, compare the thickness of a layer in a wide section with one in a narrow section.

Solution

1. The cross-sectional area increases as the water rises. Because each equal amount of water spreads over a larger area, the water height rises quickly at first and then more slowly. 2. The graph increases, but its slope decreases over time. Therefore, the graph becomes less steep. 3. If the container narrows near the top, the same amount of water produces a larger rise in height. The graph becomes steeper again in that region.

Answer

a) The water height rises more slowly over time because the container becomes wider. b) The increasing graph becomes less steep. c) The graph becomes steeper again where the container narrows.
5119188
Tim and Lisa ride the same \(3\)-mile route to an athletic field. - Tim rides at \(15\,\text{mph}\) for \(0\le s<1\) mile and at \(9\,\text{mph}\) for \(1\le s\le3\) miles. Model the change in speed at \(s=1\) as instantaneous. - Lisa rides the entire route at a constant \(12\,\text{mph}\). Imagine each rider's speed-versus-distance graph, with distance \(s\) on the x-axis and speed \(v\) on the y-axis. 1. Who has the greater speed after traveling \(0.5\) mile? 2. Who has the greater speed after traveling \(2.5\) miles? 3. At what distance do the riders have the same speed?

Hints

- Identify which segment of Tim's ride contains each stated distance. - Compare each of Tim's two speeds with Lisa's constant speed.

Solution

1. At \(s=0.5\) mile, Tim is in his first segment and rides at \(15\,\text{mph}\). Lisa rides at \(12\,\text{mph}\), so Tim is faster. 2. At \(s=2.5\) miles, Tim is in his second segment and rides at \(9\,\text{mph}\). Lisa still rides at \(12\,\text{mph}\), so Lisa is faster. 3. Lisa's speed is always \(12\,\text{mph}\). Tim's speed is either \(15\,\text{mph}\) or \(9\,\text{mph}\), so their speeds are never equal.

Answer

1. Tim 2. Lisa 3. There is no distance at which their speeds are equal.
5321818
A mountain weather station records temperature between \(6{:}00\) a.m. and \(10{:}00\) p.m. on a March day. a) Read the temperature at \(6{:}00\) a.m., \(10{:}00\) a.m., \(2{:}00\) p.m., \(6{:}00\) p.m., and \(10{:}00\) p.m. b) At what time is the temperature highest, and what is the maximum temperature? c) During what approximate time interval is the temperature above \(32\,\text{°F}\)? d) By how many degrees does the temperature rise from \(6{:}00\) a.m. to \(2{:}00\) p.m.?
Figure for problem 532181

Hints

- Read the time on the horizontal axis and temperature on the vertical axis. - The maximum is the highest point of the graph. - Find both intersections with the horizontal line \(y=32\). - Subtract the earlier temperature from the later temperature.

Solution

1. The graph gives \(23\,\text{°F}\) at \(6{:}00\) a.m., \(34\,\text{°F}\) at \(10{:}00\) a.m., \(45\,\text{°F}\) at \(2{:}00\) p.m., \(34\,\text{°F}\) at \(6{:}00\) p.m., and \(23\,\text{°F}\) at \(10{:}00\) p.m. 2. The highest point occurs at \(2{:}00\) p.m., with a maximum temperature of \(45\,\text{°F}\). 3. The graph crosses \(32\,\text{°F}\) at about \(9{:}32\) a.m. and \(6{:}28\) p.m. Thus, the temperature is above freezing between those times. 4. The increase is \(45-23=22\,\text{°F}\).

Answer

a) \(6{:}00\) a.m.: \(23\,\text{°F}\); \(10{:}00\) a.m.: \(34\,\text{°F}\); \(2{:}00\) p.m.: \(45\,\text{°F}\); \(6{:}00\) p.m.: \(34\,\text{°F}\); \(10{:}00\) p.m.: \(23\,\text{°F}\) b) \(2{:}00\) p.m.; \(45\,\text{°F}\) c) About \(9{:}32\) a.m. to \(6{:}28\) p.m. d) \(22\,\text{°F}\)
5321828
The graph shows the electrical output of a solar array, in kilowatts, from \(8{:}00\) a.m. to \(6{:}00\) p.m. A partial solar eclipse causes a temporary drop. a) What is the output at \(10{:}00\) a.m. and at \(12{:}00\) p.m.? b) During what interval does the eclipse affect the output? Give the beginning, the time of greatest obscuration, and the end. c) By what percent does output decrease from \(11{:}00\) a.m. to \(12{:}00\) p.m.?
Figure for problem 532182

Hints

- Read each requested output directly from the graph. - Compare the eclipse section with the otherwise smooth daily pattern. - Percent decrease is \(\frac{\text{decrease}}{\text{starting value}}\cdot100\%\).

Solution

1. The graph shows \(6\,\text{kW}\) at \(10{:}00\) a.m. and \(2\,\text{kW}\) at \(12{:}00\) p.m. 2. The eclipse effect begins at \(11{:}00\) a.m., reaches its greatest effect at \(12{:}00\) p.m., and ends at \(1{:}00\) p.m. 3. Output decreases from \(8\) to \(2\) kilowatts, a decrease of \(6\) kilowatts. The percent decrease is \(\frac{6}{8}=0.75=75\%\).

Answer

a) \(6\,\text{kW}\) at \(10{:}00\) a.m.; \(2\,\text{kW}\) at \(12{:}00\) p.m. b) Beginning: \(11{:}00\) a.m.; greatest effect: \(12{:}00\) p.m.; end: \(1{:}00\) p.m. c) \(75\%\)
5321948
The graph shows the temperature in a city from midnight to midnight on a fall day. a) What were the temperatures at \(9\) a.m., \(3\) p.m., and \(11\) p.m.? Record your results in a table. b) At what times was the temperature exactly \(15\,^{\circ}\text{C}\)? c) When did the daily minimum occur, and what was the temperature?
Figure for problem 532194

Hints

- Identify the quantities and units on each axis. - For a specified time, move vertically to the graph and then horizontally to the temperature axis. - For a specified temperature, trace a horizontal line and check for more than one intersection. - The lowest point of the graph gives the daily minimum.

Solution

1. Read the graph at the requested times: <table> <tr><th>Time</th><td>9 a.m.</td><td>3 p.m.</td><td>11 p.m.</td></tr> <tr><th>Temperature</th><td>\(12\,^{\circ}\text{C}\)</td><td>\(18\,^{\circ}\text{C}\)</td><td>\(9\,^{\circ}\text{C}\)</td></tr> </table> 2. The horizontal line at \(15\,^{\circ}\text{C}\) meets the graph at \(t = 11\) and \(t = 19\), corresponding to \(11\) a.m. and \(7\) p.m. 3. The lowest point is \((3, 6)\), so the minimum temperature was \(6\,^{\circ}\text{C}\) at \(3\) a.m.

Answer

a) <table> <tr><th>Time</th><td>9 a.m.</td><td>3 p.m.</td><td>11 p.m.</td></tr> <tr><th>Temperature</th><td>\(12\,^{\circ}\text{C}\)</td><td>\(18\,^{\circ}\text{C}\)</td><td>\(9\,^{\circ}\text{C}\)</td></tr> </table> b) \(11\) a.m. and \(7\) p.m. c) \(3\) a.m.; \(6\,^{\circ}\text{C}\)
5321998
Three graphs show different water-level patterns in a collection basin. Descriptions: 1) The water level decreases slowly at first and then much faster after additional valves are opened. 2) Steady rain raises the water level. After a pause in the rain, the water is pumped out quickly. 3) Rain begins lightly and becomes heavier, so the water level rises faster and faster. It then remains constant. a) Match Graphs A, B, and C with descriptions 1, 2, and 3. Explain briefly. b) In Graph B, what is the average rate at which the water level decreases during the final three hours, from \(t=3\) to \(t=6\)?
Figure for problem 532199

Hints

- Match straight, curved, and horizontal sections to the verbal descriptions. - A horizontal segment means the water level is constant. - Divide the total decrease by the elapsed time.

Solution

1. Graph A matches description 2: it rises steadily, remains constant during a rain pause, and then falls quickly. 2. Graph B matches description 1: the water level falls slowly from \(t=0\) to \(t=3\), then much faster from \(t=3\) to \(t=6\). 3. Graph C matches description 3: its increasing curve becomes steeper and then changes to a horizontal segment. 4. In Graph B, the level falls from \(9\) feet to \(0\) feet over \(3\) hours. The average decrease is \(\frac{9}{3}=3\) feet per hour.

Answer

a) \(A\to2\); \(B\to1\); \(C\to3\) b) \(3\,\text{ft/h}\) downward
5323838
The graph shows the temperature \(T\), in degrees Celsius, of a reusable heat pack after it is activated. The variable \(t\) represents the number of minutes since activation. a) Find the heat pack's initial temperature at \(t=0\). b) After how many minutes does the heat pack reach its maximum temperature, and what is that temperature? c) During what time interval is the temperature at least \(40\,\text{°C}\)? Give the start time, end time, and total duration.
Figure for problem 532383

Hints

- The initial temperature is the graph's value when \(t=0\). - The maximum temperature occurs at the highest point of the graph. - For part c), compare the graph with a horizontal line at \(40\,\text{°C}\).

Solution

1. At \(t=0\), the graph has a value of \(20\,\text{°C}\), so the initial temperature is \(20\,\text{°C}\). 2. The highest point on the graph is \((20, 45)\). Therefore, the maximum temperature is \(45\,\text{°C}\), reached after \(20\) minutes. 3. The graph is on or above \(40\,\text{°C}\) from \(t=10\) to \(t=40\). The duration is \(40-10=30\) minutes.

Answer

a) \(20\,\text{°C}\) b) After \(20\) minutes; \(45\,\text{°C}\) c) From \(10\) to \(40\) minutes; \(30\) minutes total
5324098
The graph shows the elevation profile of a mountain hike as a function of time. a) At what elevation does the hike begin, and what maximum elevation does the group reach? b) How long does the group rest at the summit? c) How many feet of elevation does the group gain during the climb? d) During the descent, after how many hours is the group at an elevation of \(2100\,\text{ft}\)?
Figure for problem 532409

Hints

- Read the first point and the highest point on the graph. - A horizontal segment represents no change in elevation. - Elevation gain is summit elevation minus starting elevation. - For part d), locate the requested elevation on the descending segment.

Solution

1. The graph begins at \(600\,\text{ft}\) and reaches a maximum of \(3000\,\text{ft}\). 2. The horizontal segment at the summit runs from \(t=4\) to \(t=6\), so the rest lasts \(6-4=2\) hours. 3. The elevation gain during the climb is \(3000-600=2400\,\text{ft}\). 4. On the descending segment, the graph reaches \(2100\,\text{ft}\) at \(t=7\).

Answer

a) Starts at \(600\,\text{ft}\); maximum \(3000\,\text{ft}\) b) \(2\) hours c) \(2400\,\text{ft}\) d) After \(7\) hours
5331758
A new car loses value quickly during its first several years. The graph shows the car's estimated resale value, in thousands of dollars, as a function of its age. a) Find the car's original price and its estimated value after \(4\) years. b) After how many years is the car worth half of its original price? c) A dealer will buy the car only after its value has fallen to \(\$6000\) or less. According to the graph, after how many years does this occur?
Figure for problem 533175

Hints

- Age \(0\) represents the car's original price. - The vertical-axis values are in thousands of dollars. - First find half of the original price, then locate that value on the graph. - For part c), locate \(6\) on the vertical axis.

Solution

1. At age \(0\), the graph shows \(24\) thousand dollars, so the original price is \(\$24{,}000\). At age \(4\), the graph shows about \(9.5\) thousand dollars, or about \(\$9500\). 2. Half of \(\$24{,}000\) is \(\$12{,}000\). The graph reaches \(12\) thousand dollars at age \(3\), so the value is halved after \(3\) years. 3. The graph reaches \(6\) thousand dollars at age \(6\). Therefore, the car is worth \(\$6000\) or less after \(6\) years.

Answer

a) \(\$24{,}000\); about \(\$9500\) after \(4\) years b) \(3\) years c) \(6\) years
5331768
A data center measures internet traffic, in gigabytes per minute, from \(6{:}00\) a.m. to \(10{:}00\) p.m. The graph shows the data rate during this \(16\)-hour period. a) At about what times do the three largest traffic peaks occur? b) About what is the data rate at \(10{:}00\) a.m.? c) Describe what happens to the graph from \(1{:}00\) p.m. to \(3{:}00\) p.m. Give one plausible reason the traffic might decrease after the early-afternoon peak. d) Estimate the lowest data rate shown.
Figure for problem 533176

Hints

- Peaks are local high points on the graph. - Use the axis scales when estimating values. - Separate what the graph shows from a possible explanation for why it happened.

Solution

1. The three largest local peaks occur at about \(8{:}00\) a.m., \(1{:}00\) p.m., and \(8{:}00\) p.m. 2. At \(10{:}00\) a.m., the graph is at about \(0.65\,\text{GB/min}\). 3. The data rate decreases from about \(2.5\,\text{GB/min}\) at \(1{:}00\) p.m. to about \(0.55\,\text{GB/min}\) at \(3{:}00\) p.m. One possible explanation is that a temporary period of heavy activity ended. The graph alone cannot establish the cause. 4. The lowest displayed rate is about \(0.5\,\text{GB/min}\).

Answer

a) About \(8{:}00\) a.m., \(1{:}00\) p.m., and \(8{:}00\) p.m. b) About \(0.65\,\text{GB/min}\) c) The data rate decreases sharply; a temporary high-activity period may have ended. d) About \(0.5\,\text{GB/min}\)
5331808
Match each description with the graph that best represents it. Briefly justify each match. a) The height of a buoy as ocean waves move it up and down over time. b) The remaining balance on a prepaid phone account when the same amount is used each day. c) The body mass of a newborn elephant during its first years of life. d) The radiation intensity of a short-lived radioactive substance as it decays.
Figure for problem 533180

Hints

- Decide whether each quantity increases, decreases, or repeats. - Look for constant change, curved change, periodic behavior, or growth that levels off.

Solution

1. Description a) matches Graph 1 because the graph repeatedly rises and falls in a periodic pattern. 2. Description b) matches Graph 2 because a constant amount used each day produces a linear decrease. 3. Description c) matches Graph 3 because the elephant's mass increases slowly at first, then more rapidly, and eventually levels off as it approaches adult size. 4. Description d) matches Graph 4 because radioactive decay decreases rapidly at first and then approaches zero more slowly.

Answer

a) Graph 1 b) Graph 2 c) Graph 3 d) Graph 4
5332178
A courier records her speed during a one-hour delivery route. The graph shows speed \(v\) as a function of time \(t\). a) What is her speed after \(5\), \(15\), \(30\), and \(50\) minutes? b) How many minutes in total is she stopped, with a speed of \(0\,\text{mph}\)? c) What is her maximum speed during the route?
Figure for problem 533217

Hints

- Read the graph at each requested time. - The courier is stopped wherever the graph lies on the time axis. - The maximum speed is the graph's highest value.

Solution

1. Reading the graph gives \(10\,\text{mph}\) at \(5\) minutes, \(20\,\text{mph}\) at \(15\) minutes, \(0\,\text{mph}\) at \(30\) minutes, and \(25\,\text{mph}\) at \(50\) minutes. 2. The graph is at \(0\) from \(t=25\) to \(t=40\), so she is stopped for \(40-25=15\) minutes. 3. The greatest y-value is \(25\), so her maximum speed is \(25\,\text{mph}\).

Answer

a) \(10\,\text{mph}\), \(20\,\text{mph}\), \(0\,\text{mph}\), \(25\,\text{mph}\) b) \(15\) minutes c) \(25\,\text{mph}\)
5332328
Four friends go on a bike ride. Each graph shows distance \(s\), in miles, as a function of time \(t\), in minutes. Match each graph with the correct description and explain your reasoning. (1) Leon rides at a constant speed. (2) Sarah rides quickly, takes a \(10\)-minute break, and then continues at a faster speed. (3) Tim starts slowly and steadily speeds up. (4) Maya starts with a sprint but gradually slows down.
Figure for problem 533232

Hints

- In a distance-time graph, slope represents speed. - A horizontal section means no distance is added. - Compare whether each graph becomes steeper or less steep over time.

Solution

1. Graph a is a straight line through the origin, so it has constant slope and represents constant speed. 2. Graph b has a horizontal section from \(t = 20\) to \(t = 30\), representing a stop. Its slope after the stop, \(0.3\,\text{mi/min}\), is greater than its slope before the stop, \(0.2\,\text{mi/min}\). 3. Graph c curves upward, so its slope increases over time. 4. Graph d curves downward, so its slope decreases over time. 5. Therefore, Leon matches a, Sarah matches b, Tim matches c, and Maya matches d.

Answer

Leon \(\rightarrow\) graph a Sarah \(\rightarrow\) graph b Tim \(\rightarrow\) graph c Maya \(\rightarrow\) graph d
5332378
Water depth was measured at a harbor throughout one day. The table shows the measurements: <table> <tr><td>Time</td><td>Midnight</td><td>3 a.m.</td><td>6 a.m.</td><td>9 a.m.</td><td>Noon</td><td>3 p.m.</td><td>6 p.m.</td><td>9 p.m.</td><td>Midnight</td></tr> <tr><td>Water depth (m)</td><td>\(3.0\)</td><td>\(5.2\)</td><td>\(3.0\)</td><td>\(0.8\)</td><td>\(3.0\)</td><td>\(5.2\)</td><td>\(3.0\)</td><td>\(0.8\)</td><td>\(3.0\)</td></tr> </table> The graph shows one possible smooth model curve through the measurements. a) Describe how the water depth changes from midnight to noon. b) At which measurement times was the greatest water depth recorded? c) What is the difference between the greatest and least measured depths?
Figure for problem 533237

Hints

- For a), read the measurements in chronological order. - For b), find the greatest table value and its times. - For c), subtract the least measurement from the greatest measurement.

Solution

1. From midnight to \(3\) a.m., the water depth rises from \(3.0\,\text{m}\) to \(5.2\,\text{m}\). It then falls to \(3.0\,\text{m}\) at \(6\) a.m. and to \(0.8\,\text{m}\) at \(9\) a.m. By noon, it rises again to \(3.0\,\text{m}\). 2. The greatest measured depth is \(5.2\,\text{m}\), recorded at \(3\) a.m. and \(3\) p.m. 3. The least measured depth is \(0.8\,\text{m}\). The difference is \(5.2\,\text{m} - 0.8\,\text{m} = 4.4\,\text{m}\).

Answer

a) The depth rises from \(3.0\,\text{m}\) to \(5.2\,\text{m}\), falls to \(0.8\,\text{m}\), and then rises to \(3.0\,\text{m}\). b) \(3\) a.m. and \(3\) p.m. c) \(4.4\,\text{m}\)
5332398
Sound level was recorded during a rock concert. The horizontal axis shows the number of minutes since recording began. Use the graph to explain: 1. When the opening band played and when the headliner began. 2. When a short stage-change break occurred.
Figure for problem 533239

Hints

- Performances are likely associated with sustained high sound levels. - A stage-change break is likely associated with a lower, flatter section.

Solution

1. After the initial rise, the sound level remains near \(85\,\text{dB}\) from about minute \(5\) to minute \(40\), so this is when the opening band likely played. The headliner likely began around minute \(65\), when the sound level rises sharply to about \(105\,\text{dB}\). 2. The stage-change break likely occurred from about minute \(45\) to minute \(60\), when the sound level remains near \(60\,\text{dB}\).

Answer

1. Opening band: about minutes \(5\)–\(40\); headliner: beginning about minute \(65\) 2. Stage-change break: about minutes \(45\)–\(60\)
5332408
The carbon dioxide concentration in a classroom is measured in parts per million. Higher values generally indicate poorer ventilation. a) What most likely happened around \(9{:}30\) a.m. and \(11{:}15\) a.m.? b) Why might the concentration decrease sharply from \(1{:}00\) p.m. to \(2{:}00\) p.m.?
Figure for problem 533240

Hints

- Consider how people in a room affect carbon dioxide concentration. - Think about actions that can improve ventilation quickly. - Distinguish a plausible explanation from something the graph proves.

Solution

1. Near \(9{:}30\) a.m. and \(11{:}15\) a.m., the concentration drops suddenly. The room was most likely ventilated by opening windows or doors. 2. A plausible explanation is that classes ended and students left the room. With fewer people exhaling carbon dioxide, the concentration decreases toward the outdoor level. The graph supports this explanation but does not prove the cause.

Answer

a) The room was most likely ventilated. b) Classes may have ended and the students may have left the room.
5332428
A delivery van leaves a depot and visits three customers in order. The graph shows the van's distance from the depot over time. a) How many total minutes does the driver spend stopped at customer locations? b) How far is the most distant customer from the depot? c) How long does the return trip to the depot take?
Figure for problem 533242

Hints

- Horizontal segments represent times when the van's distance from the depot is unchanged. - The most distant customer corresponds to the graph's greatest y-value. - Subtract the return-trip start time from its end time.

Solution

1. The horizontal segments last \(10\), \(15\), and \(10\) minutes. The total stop time is \(10+15+10=35\) minutes. 2. The greatest distance on the graph is \(8\) miles. 3. The return trip begins at \(t=75\) minutes and ends at \(t=90\) minutes, so it lasts \(15\) minutes.

Answer

a) \(35\) minutes b) \(8\) miles c) \(15\) minutes
5332468
The graph shows a roller coaster's speed as a function of the distance it has traveled along the track. a) What is the roller coaster's speed after it has traveled \(600\,\text{ft}\)? b) What is the greatest speed reached during the ride? c) After what distance does the coaster first reach a local minimum speed? Estimate the speed there. d) According to the graph, what is the total length of the track?
Figure for problem 533246

Hints

- Check what each axis represents. - High points represent local or global maximum values; low points represent local minimum values. - The endpoint of this graph represents the end of the ride.

Solution

1. At a distance of \(600\,\text{ft}\), the graph shows a speed of \(70\,\text{mph}\). 2. The highest point of the graph is \((600, 70)\), so the greatest speed is \(70\,\text{mph}\). 3. The graph first reaches a local minimum at a distance of \(300\,\text{ft}\). The speed there is about \(3\,\text{mph}\). 4. The graph ends at \((2400, 0)\), so the track is \(2400\,\text{ft}\) long.

Answer

a) \(70\,\text{mph}\) b) \(70\,\text{mph}\) c) After \(300\,\text{ft}\), at about \(3\,\text{mph}\) d) \(2400\,\text{ft}\)
5332478
A cargo ship travels through a canal. The graph shows the ship's speed \(v\), in knots, as a function of time \(t\), in minutes. a) What constant speed does the ship maintain during the open-water portions of the trip? b) The ship passes through a lock and briefly stops in the lock chamber. During what time interval is the ship stopped? c) Compare the ship's speed at time \(5\) minutes with its speed at time \(10\) minutes. d) Describe what happens from time \(11\) minutes to time \(13\) minutes.
Figure for problem 533247

Hints

- Horizontal segments represent constant speed. - A speed of \(0\) means the ship is stopped. - Use the graph's corner points to identify each interval.

Solution

1. On the horizontal sections from \(0\) to \(8\) minutes and from \(12\) to \(20\) minutes, the ship travels at \(12\) knots. 2. The graph is at \(0\) knots from \(t=9\) to \(t=11\), so the ship is stopped for that interval. 3. At \(t=5\), the speed is \(12\) knots. At \(t=10\), the speed is \(0\) knots. 4. From \(t=11\) to \(t=12\), the ship speeds up from \(0\) to \(12\) knots. From \(t=12\) to \(t=13\), it maintains \(12\) knots.

Answer

a) \(12\) knots b) From \(9\) to \(11\) minutes c) \(12\) knots at \(5\) minutes; \(0\) knots at \(10\) minutes d) The ship speeds up to \(12\) knots and then maintains that speed.
5332518
The graph shows a typical sound level at a bus terminal between \(8{:}00\) a.m. and \(8{:}00\) p.m. a) At what times do the most buses probably arrive at the same time? b) What is the maximum sound level, and when does it occur? c) Is the relation \(\text{sound level}\mapsto\text{time}\) a function? Explain.
Figure for problem 533251

Hints

- Look for the peaks of the graph and interpret what they represent. - Read the highest y-value and its corresponding time. - For the reverse relation, check whether one y-value can correspond to more than one x-value.

Solution

1. The two peaks indicate the busiest arrival times, about \(10{:}00\) a.m. and \(4{:}00\) p.m. 2. The greatest sound level is about \(90\,\text{dB}\), reached at \(10{:}00\) a.m. The second peak, at \(4{:}00\) p.m., is about \(80\,\text{dB}\). 3. No. A single sound level can occur at more than one time. Therefore, assigning a time to each sound level does not give exactly one output for every input.

Answer

a) About \(10{:}00\) a.m. and \(4{:}00\) p.m. b) About \(90\,\text{dB}\) at \(10{:}00\) a.m. c) No. The same sound level can correspond to more than one time.
5333558
Match descriptions 1–3 with Graphs A–C. Briefly justify each choice. 1) The water level in a cylindrical rain barrel during steady rainfall 2) A child's height from birth to age \(18\) 3) The height of a pendulum above a table as it swings back and forth
Figure for problem 533355

Hints

- Decide whether each quantity changes at a constant rate, levels off, or repeats. - A periodic graph represents a repeating process.

Solution

1. Description 1 matches Graph A. Steady rainfall adds water at a constant volume rate, and a cylindrical barrel has constant cross-sectional area, so water height increases linearly. 2. Description 2 matches Graph B. A child grows rapidly at first, then more slowly, and height eventually levels off near adulthood. 3. Description 3 matches Graph C. A pendulum's height rises and falls in a repeating periodic pattern.

Answer

1) Graph A 2) Graph B 3) Graph C
5333568
Each graph represents a quantity changing over time. Match each situation with its graph. 1) A car's value decreases over the years, but the rate of decrease becomes slower. 2) A bacterial population grows slowly at first, then rapidly, and finally levels off when space becomes limited. 3) A car accelerates and then continues at a constant speed.
Figure for problem 533356

Hints

- Decide whether each graph rises or falls. - Look for exponential decay, S-shaped growth, and a rise followed by a constant value.

Solution

1. Situation 1 matches Graph A. The graph decreases rapidly at first and then flattens, which is characteristic of exponential decay. 2. Situation 2 matches Graph B. Its S-shape represents slow initial growth, rapid growth, and then a limiting population. 3. Situation 3 matches Graph C. The speed first increases and then remains constant, represented by a rising segment followed by a horizontal segment.

Answer

1) Graph A 2) Graph B 3) Graph C
5337468
The graph shows the elevation profile of a hike. The horizontal axis shows distance in miles, and the vertical axis shows elevation in feet. a) At what distance did the hikers reach the highest point? What was the elevation? b) At what distance was the elevation lowest? c) During which parts of the hike did the hikers travel uphill?
Figure for problem 533746

Hints

- Use the axis labels to identify the units. - The highest point is the greatest vertical value on the graph. - The hikers are traveling uphill wherever the graph rises from left to right.

Solution

1. The greatest elevation on the graph occurs at mile \(8\), where the elevation is \(1500\,\text{ft}\). 2. The least elevation is \(800\,\text{ft}\) at mile \(0\). 3. The graph rises from mile \(0\) to mile \(2\) and from mile \(5\) to mile \(8\).

Answer

a) At mile \(8\); \(1500\,\text{ft}\) b) At mile \(0\) c) From mile \(0\) to mile \(2\), and from mile \(5\) to mile \(8\)
5337958
The graph shows the concentration of a pollutant in a river after a chemical spill. The variable \(t\) is the number of hours since the spill, and \(c\) is the concentration in milligrams per liter. a) Find the pollutant concentration exactly \(6\) hours after the spill. b) During what time interval is the concentration greater than \(40\,\text{mg/L}\)?
Figure for problem 533795

Hints

- Read the graph at \(t=6\). - Compare the graph with a horizontal line at \(c=40\). - Because the problem says “greater than,” do not include the boundary times.

Solution

1. At \(t=6\), the graph has a value of \(30\,\text{mg/L}\). 2. The graph is at \(40\,\text{mg/L}\) at \(t=1\) and \(t=4\). Between those times, it is above \(40\,\text{mg/L}\). Because the inequality is strict, the concentration is greater than \(40\,\text{mg/L}\) for \(1<t<4\).

Answer

a) \(30\,\text{mg/L}\) b) \(1<t<4\) hours
5338878
The graph shows the temperature \(T\), in degrees Fahrenheit, as a function of time \(t\), in hours, on a spring morning. Read each value from the graph. a) Find \(T(1)\). b) Find \(T(3)\). c) Find \(T(2)-T(4)\). d) At what times is the temperature exactly \(34\,\text{°F}\)?
Figure for problem 533887

Hints

- Check which quantity appears on each axis. - To find \(T(1)\), begin at \(1\) on the horizontal axis and move vertically to the graph. - Read both function values before subtracting. - For a specified temperature, look for every point where the graph has that y-value.

Solution

1. At \(t=1\), the graph has a value of \(38\), so \(T(1)=38\,\text{°F}\). 2. At \(t=3\), the graph has a value of \(30\), so \(T(3)=30\,\text{°F}\). 3. The graph shows \(T(2)=34\) and \(T(4)=34\). Therefore, \(T(2)-T(4)=34-34=0\,\text{°F}\). 4. The graph has a value of \(34\,\text{°F}\) at \(t=0\), \(t=2\), and \(t=4\) hours.

Answer

a) \(38\,\text{°F}\) b) \(30\,\text{°F}\) c) \(0\,\text{°F}\) d) At \(t=0\), \(t=2\), and \(t=4\) hours
5338888
A company models its profit \(P\), in thousands of dollars, as a function of the number \(x\) of production units. Use the graph to answer the questions. a) What is the profit when \(x=3\)? b) Find \(P(4)\). c) Find the change in profit when production increases from \(x=1\) to \(x=2\). d) At what production levels does the company break even?
Figure for problem 533888

Hints

- Account for the fact that the vertical axis is measured in thousands of dollars. - A function value is the y-coordinate corresponding to the given x-coordinate. - To find a change, subtract the earlier function value from the later one. - Break-even points are x-intercepts.

Solution

1. At \(x=3\), the graph has a y-value of \(4\). Because profit is measured in thousands of dollars, the profit is \(\$4000\). 2. At \(x=4\), the graph has a y-value of \(3\), so \(P(4)=3\), representing \(\$3000\). 3. The graph shows \(P(1)=0\) and \(P(2)=3\). Thus, \(P(2)-P(1)=3-0=3\), so profit increases by \(\$3000\). 4. The graph crosses the x-axis at \(x=1\) and \(x=5\). These are the break-even production levels.

Answer

a) \(\$4000\) b) \(P(4)=3\), or \(\$3000\) c) An increase of \(\$3000\) d) \(x=1\) and \(x=5\)
5349148
Lucas rides his bike from home to a friend’s house and then returns home. The graph shows his distance from home, in miles, as a function of time, in minutes. 1) How far from home is Lucas after \(10\) minutes? 2) How long does he stop during the trip? 3) On the return trip, after how many minutes is Lucas exactly \(1.5\) miles from home? 4) How many miles does Lucas ride altogether?
Figure for problem 534914

Hints

- The horizontal axis shows time, and the vertical axis shows distance from home. - A horizontal segment means time passes while the distance stays the same. - The return trip is the part where the distance from home decreases. - For the total distance, include both the trip away from home and the trip back.

Solution

1. At \(10\) minutes, the graph shows a distance of \(3\) miles. 2. The graph is horizontal from \(10\) to \(15\) minutes, so the stop lasts \(15 - 10 = 5\) minutes. 3. On the return trip, the distance decreases from \(3\) miles at \(15\) minutes to \(0\) miles at \(25\) minutes. The graph reaches \(1.5\) miles halfway through that interval, at \(20\) minutes. 4. Lucas rides \(3\) miles to his friend’s house and \(3\) miles home, for a total of \(3 + 3 = 6\) miles.

Answer

1) \(3\) miles 2) \(5\) minutes 3) \(20\) minutes 4) \(6\) miles
5349168
The graph shows the temperature in a garden during a \(24\)-hour spring day. 1. What was the temperature at \(6{:}00\) a.m. and at \(2{:}00\) p.m.? 2. At what times was the temperature exactly \(32\,{}^\circ\text{F}\)? 3. What was the lowest temperature, and when did it occur? 4. During what time interval did the temperature rise continuously?
Figure for problem 534916

Hints

- The horizontal axis shows the hour of the day, and the vertical axis shows temperature. - To find when the temperature was \(32\,{}^\circ\text{F}\), find where the graph crosses that horizontal level. - The lowest point gives the minimum temperature. - The temperature rises wherever the graph moves upward from left to right.

Solution

1. At hour \(6\), the graph shows \(28\,{}^\circ\text{F}\). At hour \(14\), it shows \(43\,{}^\circ\text{F}\). 2. The graph reaches \(32\,{}^\circ\text{F}\) at hour \(4\) and hour \(11\), which are \(4{:}00\) a.m. and \(11{:}00\) a.m. 3. The lowest point is \(26\,{}^\circ\text{F}\) at \(8{:}00\) a.m. 4. The graph rises continuously from hour \(8\) to hour \(17\), or from \(8{:}00\) a.m. to \(5{:}00\) p.m.

Answer

1. \(28\,{}^\circ\text{F}\) at \(6{:}00\) a.m.; \(43\,{}^\circ\text{F}\) at \(2{:}00\) p.m. 2. \(4{:}00\) a.m. and \(11{:}00\) a.m. 3. \(26\,{}^\circ\text{F}\) at \(8{:}00\) a.m. 4. From \(8{:}00\) a.m. to \(5{:}00\) p.m.
5349208
The graph shows a function \(f\). Use the graph to answer each question. 1) Find \(f(-3)\), \(f(-1)\), and \(f(3)\). 2) For which values of \(x\) is \(f(x)=0\)? 3) State the domain and range of \(f\). 4) For which values of \(x\) in the displayed domain is \(f(x)>0\)?
Figure for problem 534920

Hints

- To find \(f(x)\), locate the input on the x-axis and read the corresponding y-coordinate. - Zeros occur where the graph meets the x-axis. - The domain is the horizontal extent of the graph, and the range is its vertical extent. - Positive outputs occur where the graph lies above the x-axis.

Solution

1. Read the y-coordinate of the graph at each input: \(f(-3)=0\), \(f(-1)=2\), and \(f(3)=-2\). 2. The graph meets the x-axis at \(x=-3\), \(x=1\), and \(x=5\). 3. The graph extends from \(x=-4\) through \(x=5\), so the domain is \([-4, 5]\). Its lowest output is \(-3\) and its highest output is \(2\), so the range is \([-3, 2]\). 4. The graph is above the x-axis between the zeros \(-3\) and \(1\), so \(f(x)>0\) for \(-3<x<1\).

Answer

1) \(f(-3)=0\), \(f(-1)=2\), and \(f(3)=-2\) 2) \(x\in\{-3, 1, 5\}\) 3) Domain: \([-4, 5]\); range: \([-3, 2]\) 4) \(-3<x<1\)
5349678
The four panels show different function graphs. Which graph, a, b, c, or d, represents the square root function \(f(x) = \sqrt{x}\)? Justify your choice by checking whether the point \(P(4, 2)\) lies on the graph.
Figure for problem 534967

Hints

- For which inputs is a real square root defined? - Compare the typical shapes of quadratic, reciprocal, and linear function graphs. - Evaluate the function at simple inputs such as \(1\), \(4\), and \(9\). - Match the resulting points to the displayed graphs.

Solution

1. Graph a is a parabola, graph c is a reciprocal-function graph, and graph d is a line. 2. The square root function is defined for \(x \geq 0\), begins at \((0, 0)\), increases, and becomes less steep as \(x\) increases. Graph b has these features. 3. Evaluate the function at \(x = 4\): \(f(4) = \sqrt{4} = 2\). Therefore, \(P(4, 2)\) lies on the square root graph. 4. Among the four panels, only graph b has the correct shape and passes through \((4, 2)\).

Answer

Graph b represents \(f(x) = \sqrt{x}\).
5119178
A car travels along a \(6\)-mile route. A speed-versus-distance graph has the following features. - From \(s=0\) to \(s=1\) mile, the speed increases steadily from \(0\) to \(30\,\text{mph}\). - For \(1\le s<5\), the speed remains \(30\,\text{mph}\). - At exactly \(s=5\) miles, the speed is \(0\,\text{mph}\), while immediately before and after that location it is \(30\,\text{mph}\). - For \(5<s\le6\), the speed remains \(30\,\text{mph}\). a) What might have happened at mile \(5\)? b) Why can the duration of a stop, such as waiting at a red light, not be read from this type of speed-versus-distance graph?

Hints

- Consider what a speed of \(0\) means. - Identify the quantity on the horizontal axis. - Think about what an odometer does while a car is stopped.

Solution

1. A speed of \(0\,\text{mph}\) at mile \(5\), with positive speed immediately before and after, represents an idealized stop at that location, such as a red light or stop sign. 2. The horizontal axis shows distance, not time. During a stop, the car's distance does not change, so the entire waiting period occurs at the single distance \(s=5\). The graph can show that the speed there is \(0\), but it cannot show how long the stop lasts.

Answer

a) The car made an idealized stop at mile \(5\), perhaps at a traffic signal or stop sign. b) Distance remains fixed during the stop, and the graph has no time axis, so the waiting time is not represented.
5321788
Luke measures the temperature of a pot of tea every \(5\) minutes and marks the measurements with red crosses. He draws two graphs through the measurements: - Graph A connects consecutive points with line segments. - Graph B uses a smooth, continuous curve. a) Explain why Graph B is a better physical model of the tea's cooling process. b) Use Graph B to estimate the tea's temperature after \(12\) minutes. c) According to Graph B, after about how many minutes does the tea cool to \(104\,\text{°F}\)?
Figure for problem 532178

Hints

- Think about what a corner in Graph A says about the cooling rate. - For a temperature at a given time, move vertically from the time to Graph B. - For a given temperature, move horizontally to Graph B and then down to the time axis.

Solution

1. A liquid's temperature changes continuously, and its cooling rate does not suddenly jump at each measurement time. The corners in Graph A represent abrupt rate changes, while Graph B represents a smooth physical process. 2. At \(t=12\) minutes, Graph B is at about \(121\,\text{°F}\). A reasonable graph-reading range is approximately \(119\)–\(122\,\text{°F}\). 3. The horizontal line \(T=104\) intersects Graph B at about \(18.4\) minutes, so an estimate of \(18\) to \(19\) minutes is reasonable.

Answer

a) Graph B is smoother and better represents continuous cooling without abrupt changes in rate. b) About \(121\,\text{°F}\) c) About \(18\) to \(19\) minutes
5321878
Lara, Max, and Sophie ride bicycles from one town to another \(12\) miles away. Lara rides at a constant speed. Max stops because of a flat tire and then continues riding. Sophie gradually speeds up. The graph shows distance traveled as a function of riding time. a) Match Lara, Max, and Sophie to Graph A, B, or C and explain. b) Use the graph to answer. 1. Who arrives first, and how long does the trip take? 2. How long is Max stopped because of the flat tire? 3. How far has Lara traveled after \(40\) minutes?
Figure for problem 532187

Hints

- Constant speed produces a straight line. - A horizontal segment means no distance is added. - A graph that becomes steeper represents increasing speed. - The first graph to reach the target distance represents the earliest arrival.

Solution

1. Lara rides at a constant speed, so her graph is the straight line A. Max rides, stops, and then continues faster, so his graph is the piecewise-linear Graph B with a horizontal segment. Sophie speeds up over time, so her graph becomes progressively steeper and is Graph C. 2. Graph B reaches \(12\) miles at \(70\) minutes, Graph A at \(80\) minutes, and Graph C at \(90\) minutes. Max arrives first in \(70\) minutes. 3. Max's horizontal segment runs from minute \(20\) to minute \(50\), so he is stopped for \(30\) minutes. 4. Graph A reaches \(6\) miles at \(40\) minutes.

Answer

a) Lara: A; Max: B; Sophie: C b) 1. Max, \(70\) minutes 2. \(30\) minutes 3. \(6\) miles
5322018
Containers A and B are each filled at a constant volume rate. Each container consists of two stacked cylinders with different diameters. - Container A is narrow on the bottom and wide on top. - Container B is wide on the bottom and narrow on top. Graphs 1 and 2 show water height as a function of time. a) Which graph belongs to each container? Explain using the changes in slope. b) For each container, find the height of the lower cylinder where the diameter changes.
Figure for problem 532201

Hints

- Water height rises faster in a narrower cross section. - A greater slope means a faster increase in height. - The corner in each graph marks the boundary between the two cylinders.

Solution

1. In a narrow cylinder, the same added volume produces a faster rise in water height, so the graph is steeper. 2. Graph 2 begins steeply and then becomes less steep. Therefore, Graph 2 represents Container A, which is narrow below and wide above. 3. Graph 1 begins less steeply and then becomes steeper. Therefore, Graph 1 represents Container B, which is wide below and narrow above. 4. The change in diameter occurs at each graph's corner. For Container A, the corner is at a height of \(4\,\text{cm}\). For Container B, it is at \(2\,\text{cm}\).

Answer

a) Container A: Graph 2; Container B: Graph 1 b) Container A: \(4\,\text{cm}\); Container B: \(2\,\text{cm}\)
5322128
The graphs show the elevation profiles of two hiking trails, Trail A and Trail B. a) For each trail, find the starting elevation and ending elevation. Then find the change in elevation from start to finish. b) Find the maximum elevation on each trail and the distance at which it occurs. c) Which trail has more total elevation gain? Support your answer by adding the gains from all uphill sections.
Figure for problem 532212

Hints

- Read the elevation at the starting and ending distances. - Find the highest point on each graph. - Total elevation gain includes only uphill changes, not downhill changes.

Solution

1. Trail A starts at \(400\,\text{ft}\) and ends at \(600\,\text{ft}\), for a net change of \(600 - 400 = 200\,\text{ft}\). Trail B starts at \(200\,\text{ft}\) and ends at \(900\,\text{ft}\), for a net change of \(900 - 200 = 700\,\text{ft}\). 2. Trail A reaches a maximum elevation of \(800\,\text{ft}\) at mile \(9\). Trail B reaches a maximum elevation of \(900\,\text{ft}\) at mile \(15\). 3. Trail A has one overall uphill section from \(300\,\text{ft}\) to \(800\,\text{ft}\), a gain of \(500\,\text{ft}\). 4. Trail B gains \(700 - 200 = 500\,\text{ft}\), then later gains \(900 - 500 = 400\,\text{ft}\). Its total elevation gain is \(500 + 400 = 900\,\text{ft}\). 5. Trail B has more total elevation gain.

Answer

a) Trail A: start \(400\,\text{ft}\), end \(600\,\text{ft}\), net change \(200\,\text{ft}\) Trail B: start \(200\,\text{ft}\), end \(900\,\text{ft}\), net change \(700\,\text{ft}\) b) Trail A: \(800\,\text{ft}\) at mile \(9\) Trail B: \(900\,\text{ft}\) at mile \(15\) c) Trail B; Trail A gains \(500\,\text{ft}\), while Trail B gains \(900\,\text{ft}\).
5332358
A startup tracks its monthly revenue and expenses during its first year. The graph shows both amounts in thousands of dollars. a) During which whole-numbered months is revenue greater than expenses? b) During which month is the loss greatest? c) Estimate when revenue and expenses are equal.
Figure for problem 533235

Hints

- Profit occurs when revenue is above expenses. - The greatest loss occurs where the vertical gap is largest with expenses on top. - Equal amounts occur at the intersection.

Solution

1. The company earns a profit when the revenue graph lies above the expense graph. The graphs cross between months \(6\) and \(7\), so revenue is greater than expenses during months \(7\) through \(12\). 2. The loss is greatest where the expense graph is farthest above the revenue graph. That occurs in month \(1\). 3. The graphs intersect at about \(x=6.5\), between months \(6\) and \(7\).

Answer

a) Months \(7\) through \(12\) b) Month \(1\) c) About \(x=6.5\), between months \(6\) and \(7\)
5332488
A dog runs back and forth along a straight path from its owner. The graph shows the dog’s distance from the owner over time. a) How far is the dog from its owner after \(20\,\text{s}\)? b) During which time intervals does the dog’s distance from its owner remain constant? c) When is the dog farthest from its owner? d) Find the total distance the dog runs during the \(120\) seconds.
Figure for problem 533248

Hints

- A horizontal section means the distance from the owner is unchanged. - Distance from the owner is not the same as total distance traveled. - Add the absolute change in distance over each moving interval.

Solution

1. At \(t = 20\,\text{s}\), the distance is \(120\,\text{ft}\). 2. Horizontal sections show constant distance. These occur from \(20\) to \(50\) seconds and from \(70\) to \(90\) seconds. 3. The greatest distance is \(120\,\text{ft}\), reached from \(20\) to \(50\) seconds. 4. From \(0\) to \(20\) seconds, the dog runs \(120\,\text{ft}\) away. From \(50\) to \(70\) seconds, it runs \(120 - 30 = 90\,\text{ft}\) toward the owner. From \(90\) to \(120\) seconds, it runs another \(30\,\text{ft}\) toward the owner. 5. The total distance is \(120 + 90 + 30 = 240\,\text{ft}\).

Answer

a) \(120\,\text{ft}\) b) From \(20\) to \(50\) seconds and from \(70\) to \(90\) seconds c) From \(20\) to \(50\) seconds, at a distance of \(120\,\text{ft}\) d) \(240\,\text{ft}\)
5332548
The graph shows the water level in a harbor over a \(12\)-hour period beginning at midnight. a) Find the highest and lowest water levels and the times when they occur. b) A small vessel can maneuver safely only when the water level is at least \(6\,\text{ft}\). During what time intervals is this possible? c) During which two-hour intervals does the water level rise the most? d) Estimate how many feet the water level drops from \(4{:}00\) a.m. to \(6{:}00\) a.m.
Figure for problem 533254

Hints

- Maximum and minimum values occur at the graph's highest and lowest points. - For part b), compare the graph with a horizontal line at \(6\). - Compare the vertical changes over two-hour intervals. - For part d), subtract the later water level from the earlier one.

Solution

1. The maximum water level is \(15\,\text{ft}\) at \(3{:}00\) a.m. The minimum is \(3\,\text{ft}\) at \(9{:}00\) a.m. 2. The graph is at or above \(6\,\text{ft}\) from midnight to \(7{:}00\) a.m. and again from \(11{:}00\) a.m. to noon. 3. Comparing two-hour increases, the greatest rises occur from midnight to \(2{:}00\) a.m. and from \(10{:}00\) a.m. to noon. 4. At \(4{:}00\) a.m., the water level is about \(14.2\,\text{ft}\); at \(6{:}00\) a.m., it is \(9\,\text{ft}\). The level drops by about \(14.2-9=5.2\,\text{ft}\).

Answer

a) Highest: \(15\,\text{ft}\) at \(3{:}00\) a.m.; lowest: \(3\,\text{ft}\) at \(9{:}00\) a.m. b) Midnight–\(7{:}00\) a.m. and \(11{:}00\) a.m.–noon c) Midnight–\(2{:}00\) a.m. and \(10{:}00\) a.m.–noon d) About \(5.2\,\text{ft}\)
5349228
For a school project, Lucas measured the height of a bean plant over two weeks. The graph shows his measurements. 1. How tall was the plant on day \(4\)? 2. According to the line between the plotted measurements, how tall was the plant on day \(7\)? 3. After how many days did the plant reach a height of \(60\,\text{mm}\)? 4. How many millimeters did the plant grow from day \(4\) to day \(12\)? 5. Make a table showing the plant’s height on each even-numbered day from day \(0\) through day \(14\).
Figure for problem 534922

Hints

- Use the axis labels to identify time and height. - Follow grid lines between an axis value and the graph. - For day \(7\), use the straight segment between the measurements on days \(6\) and \(8\). - Growth is the difference between the final height and the initial height.

Solution

1. At day \(4\), the graph shows \(10\,\text{mm}\). 2. Day \(7\) is halfway between day \(6\), at \(30\,\text{mm}\), and day \(8\), at \(50\,\text{mm}\). The straight segment gives \(30 + \frac{50 - 30}{2} = 40\,\text{mm}\). 3. The graph reaches \(60\,\text{mm}\) at day \(10\). 4. The plant’s height changes from \(10\,\text{mm}\) on day \(4\) to \(65\,\text{mm}\) on day \(12\). The growth is \(65 - 10 = 55\,\text{mm}\). 5. The values read from the graph are: <table> <thead> <tr><th>Day</th><th>\(0\)</th><th>\(2\)</th><th>\(4\)</th><th>\(6\)</th><th>\(8\)</th><th>\(10\)</th><th>\(12\)</th><th>\(14\)</th></tr> </thead> <tbody> <tr><td>Height (mm)</td><td>\(0\)</td><td>\(0\)</td><td>\(10\)</td><td>\(30\)</td><td>\(50\)</td><td>\(60\)</td><td>\(65\)</td><td>\(70\)</td></tr> </tbody> </table>

Answer

1. \(10\,\text{mm}\) 2. \(40\,\text{mm}\) 3. \(10\) days 4. \(55\,\text{mm}\) 5. <table> <thead> <tr><th>Day</th><th>\(0\)</th><th>\(2\)</th><th>\(4\)</th><th>\(6\)</th><th>\(8\)</th><th>\(10\)</th><th>\(12\)</th><th>\(14\)</th></tr> </thead> <tbody> <tr><td>Height (mm)</td><td>\(0\)</td><td>\(0\)</td><td>\(10\)</td><td>\(30\)</td><td>\(50\)</td><td>\(60\)</td><td>\(65\)</td><td>\(70\)</td></tr> </tbody> </table>
5349688
The graph shows \(f(x) = \sqrt{x}\) and \(g(x) = 0.5x\). 1. Use the graph to find the intersection points. 2. For which \(x\)-values in \(0 < x < 5\) is the square root function above the line? Explain using the graph.
Figure for problem 534968

Hints

- Intersection points occur where the two functions have the same output. - Compare which graph is higher in each interval. - Use the intersection points as boundaries when comparing the graphs.

Solution

1. The graphs intersect at \((0, 0)\) and \((4, 2)\). 2. Between the intersection points, the graph of \(f\) is above the graph of \(g\). Therefore, \(\sqrt{x} > 0.5x\) for \(0 < x < 4\). 3. At \(x = 4\), the functions are equal. For \(4 < x < 5\), the line is above the square root graph.

Answer

1. The intersection points are \((0, 0)\) and \((4, 2)\). 2. The square root function is above the line for \(0 < x < 4\).
5349768
The graph of \(f\) is shown on the interval \([-4, 4]\). For each interval, find the greatest and least function values. 1) \(I_1=[-3, 0]\) 2) \(I_2=[0, 3]\) 3) \(I_3=[-4, 4]\)
Figure for problem 534976

Hints

- Restrict your attention to the portion of the graph whose x-values are in the stated interval. - Compare all local high and low points and both endpoints of the interval. - The greatest function value is the highest y-value; the least function value is the lowest y-value.

Solution

1. On \([-3, 0]\), the least value is \(-4\) at \(x=-2\). The greatest value is the endpoint value \(f(0)=0\). 2. On \([0, 3]\), the greatest value is \(4\) at \(x=2\). The least value is the endpoint value \(f(0)=0\). 3. On \([-4, 4]\), the greatest value is \(4\), reached at \(x=-4\) and \(x=2\). The least value is \(-4\), reached at \(x=-2\) and \(x=4\).

Answer

1) Greatest: \(0\); least: \(-4\) 2) Greatest: \(4\); least: \(0\) 3) Greatest: \(4\); least: \(-4\)
5350278
Use the graph of \(f\). Which interval contains a solution of \((f(x))^2=4\)? 1) \([-4, -3]\) 2) \([-2, -1]\) 3) \([0, 1]\) 4) \([1, 2]\)
Figure for problem 535027

Hints

- Determine the two possible values of \(f(x)\) whose squares equal \(4\). - Find where the graph has either of those y-values. - Check which listed interval contains one of the corresponding x-values.

Solution

1. The equation \((f(x))^2=4\) means \(f(x)=2\) or \(f(x)=-2\). 2. The graph intersects \(y=2\) at approximately \(x=-3.46\) and \(x=3.46\). 3. The graph never reaches \(y=-2\), because its minimum value is \(-1\). 4. Of the listed intervals, only \([-4, -3]\) contains one of the solutions.

Answer

1) \([-4, -3]\)

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