Problem 8 · 2013 Math Kangaroo
Easy
Fractions, Decimals & Percents
Number Theory
divisiontotal-then-divide
Marie works out the average number of children per family in her village. Five families live in the village. Which of these values could she not get?
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Answer: C — 1.3
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Hint 1 of 2
The average is the total number of children divided by 5.
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Hint 2 of 2
So the average must be a whole number of fifths — a multiple of 0.2.
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Approach: average must be a multiple of 1/5
- With 5 families, the average equals (total children) ÷ 5.
- The total is a whole number, so the average must be a multiple of 0.2.
- 1.0, 1.2, 1.4, 2.0 are multiples of 0.2, but 1.3 is not.
- So she could not get 1.3.
Mark:
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