Problem 11 · 2009 Math Kangaroo
Medium
Logic & Word Problems
careful-counting
A farmer has 30 cows, some chickens and no other animals. The total number of chicken legs is equal to the total number of cow legs. How many animals does the farmer have?
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Answer: B — 90
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Hint 1 of 2
Count the cow legs first.
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Hint 2 of 2
Chicken legs match cow legs, so work out how many chickens that is.
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Approach: match leg counts, then total the animals
- 30 cows have 30 × 4 = 120 legs.
- The chickens have the same number of legs: 120.
- Each chicken has 2 legs, so there are 120 ÷ 2 = 60 chickens.
- Altogether: 30 + 60 = 90 animals.
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