Problem 10 · 2022 Math Kangaroo
Medium
Arithmetic & Operations
sum-constraint
The kangaroos in a family are 2, 4, 5, 6, 8 and 10 years old. Four of them add up to 22 years. How old are the other two kangaroos?
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Answer: C — 5 and 8
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Hint 1 of 3
Add up all six ages first to get the grand total.
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Hint 2 of 3
If four of them add to 22, the two left over must make up the rest of the total.
Still stuck? Show hint 3 →
Hint 3 of 3
Take 22 away from the grand total, then find which two ages on the list add to that.
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Approach: add all the ages, then take away 22
- All six ages add up to 2 + 4 + 5 + 6 + 8 + 10 = 35.
- If four of them make 22, the other two must make 35 − 22 = 13.
- On the list, the pair that adds to 13 is 5 and 8.
- So the other two kangaroos are 5 and 8 (choice C).
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