1956 AMC 12 Problem 32

Attempt Problem 32 of the 1956 AMC 12 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1956 AMC 12 solutions, or check the answer key.

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32.

George and Henry started a race from opposite ends of the pool. After a minute and a half, they passed each other in the center of the pool. If they lost no time in turning and maintained their respective speeds, how many minutes after starting did they pass each other the second time?

33

4124\dfrac12

66

7127\dfrac12

99

Answer: B
Concepts:constant speedreflected motionperiodic motion
Difficulty rating: 1550
Small Hint:

Meeting at the center means the two swimmers have equal speeds

Big Hint:

They reach the opposite ends at 33 minutes, turn, and need another half-pool each

Solution:

Because they started simultaneously from opposite ends and first met at the center, their speeds are equal. Each reaches the opposite end after 33 minutes. They turn immediately, and each then needs another 1.51.5 minutes to return to the center, where they meet again. The second meeting occurs after 3+1.5=4.5=412 3+1.5=4.5=4\frac12 minutes.

Thus, the correct answer is B.

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