Calculate \(5\div\frac{1}{9}\) and \(4\div\frac{1}{11}\), then compare the quotients. Explain why a rough estimate based only on both denominators being close to \(10\) could not reliably decide this close comparison.
Hints
- Use estimation only to recognize that the two answers should be close.
- For each expression, count the unit-fraction pieces in one whole and then in all the wholes.
- Compare the exact counts and explain why their small difference matters.
Solution
1. Both divisors are unit fractions with denominators close to \(10\), and the dividends differ by only \(1\). A rough estimate would place both quotients near the mid-forties, so it would not settle which is greater.
2. \(5\div\frac{1}{9}=45\), because \(5\) wholes contain \(5\times9\) ninths.
3. \(4\div\frac{1}{11}=44\), because \(4\) wholes contain \(4\times11\) elevenths.
4. Therefore the first quotient is greater by \(1\). Exact calculation is needed for this near-tie.
Answer
\(5\div\frac{1}{9}=45\) and \(4\div\frac{1}{11}=44\). The first is greater by \(1\); rough estimation alone does not resolve the near-tie.