2006 AMC 12B Problem 5

Below is the professionally curated solution for Problem 5 of the 2006 AMC 12B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2006 AMC 12B solutions, or check the answer key.

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Concepts:relative speeddistance rate and time

Difficulty rating: 1100

5.

John is walking east at a speed of 33 miles per hour, while Bob is also walking east, but at a speed of 55 miles per hour. If Bob is now 11 mile west of John, how many minutes will it take for Bob to catch up to John?

3030

5050

6060

9090

120120

Solution:

Bob closes the gap at a relative speed of 53=25 - 3 = 2 miles per hour. To cover the 11-mile gap takes 12 hour=30 minutes.\frac{1}{2} \text{ hour} = 30 \text{ minutes}.

Thus, the correct answer is A.

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