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Students are asked to evaluate \(0.4 \times \frac{5}{11} + 0.7 \times \frac{5}{11}\).
Luke finds the two products separately and then adds them.
Maria uses the distributive property and factors out the common factor \(\frac{5}{11}\).
a) Find the value using Maria’s method.
b) Compare the methods. What advantage does Maria’s method have?
Hints
- Look for a factor that appears in both terms.
- Use the distributive property to factor out the common factor.
- Add the decimals before multiplying by the fraction.
Solution
1. Factor out the common factor: \((0.4 + 0.7) \times \frac{5}{11}\).
2. Add inside the parentheses: \(0.4 + 0.7 = 1.1\).
3. Write \(1.1\) as a fraction: \(1.1 = \frac{11}{10}\).
4. Multiply and simplify: \(\frac{11}{10} \times \frac{5}{11} = \frac{1}{2}\).
5. Maria’s method uses one multiplication instead of two, and the factors simplify immediately.
Answer
a) The value is \(\frac{1}{2}\), or \(0.5\).
b) Maria’s method is more efficient because it uses one multiplication and allows immediate simplification.
