Problem 4 · 2019 Math Kangaroo
Easy
Logic & Word Problems
off-by-one
There are 12 children in front of a zoo. Susi is the 7th from the front and Kim is the 2nd from the back. How many children are there between Susi and Kim?
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Answer: B — 3
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Hint 1 of 2
Find Susi's and Kim's spots in the line first, counting from the same end.
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Hint 2 of 2
Once you know both positions, count only the children strictly in between them.
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Approach: place both children by position, then count the gap
- Counting from the front, Susi is in spot 7.
- Kim is 2nd from the back of 12, so Kim is in spot 11.
- The children between them sit in spots 8, 9 and 10.
- That is 3 children, so the answer is B.
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