Problem 5 · 2013 Math Kangaroo
Easy
Arithmetic & Operations
ages
Anna, Bob and Chris are altogether 31 years old. How old will all three be altogether in three years’ time?
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Answer: E — 40
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Hint 1 of 2
You don't need each person's age, only how much the total grows.
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Hint 2 of 2
Every birthday adds 1 year, so in 3 years each of the three people adds 3 years.
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Approach: add 3 years for each of the three people
- Right now the three ages add up to 31.
- In three years every person is 3 years older, so the total goes up by \(3 \times 3 = 9\).
- New total \(= 31 + 9 = 40\), which is choice E.
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