Problem 9 · 2017 Math Kangaroo
Hard
Fractions, Decimals & Percents
fraction-to-decimalpercent-multiplier
At a wedding one eighth of the guests is underage. Three sevenths of the adult guests are men. How big is the fraction of adult women amongst all guests?
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Answer: A — 12
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Hint 1 of 2
What fraction of all guests are adults?
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Hint 2 of 2
Find the men as a fraction of all guests, then take what is left of the adults.
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Approach: take fractions of fractions, all relative to the whole party
- Underage guests are 1/8 of everyone, so adults are 7/8 of all guests.
- Men are 3/7 of the adults: 3/7 × 7/8 = 3/8 of all guests.
- Adult women = adults − men = 7/8 − 3/8 = 4/8 = 1/2, choice A.
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