Question

11. A man rowed 3 miles upstream in 90 minutes. If the river flowed witha current of 2

miles per hour, how long did the man's return trip take?
(A) 20 minutes
minutes (E) 80 minutes
(B) 30 minutes
(C) 45 minutes
(D)
60

Answer 1

The man's return trip took approximately 1.525 minutes.

Step-by-step explanation:

To solve this problem, we can use the concept of relative velocity. The man's rowing speed is given by the distance he covers divided by the time taken. Since he is rowing upstream, we subtract the speed of the current from his rowing speed to get his effective rowing speed. Thus, his rowing speed is 3 miles / 90 minutes = 1/30 miles per minute, and the effective rowing speed is (1/30) - 2 = -59/30 miles per minute (since the river is flowing in the opposite direction). We can now find the time taken for the return trip by dividing the distance by the effective rowing speed. The distance is 3 miles and the effective rowing speed is (-59/30) miles per minute. Dividing the distance by the speed gives us 3 / (-59/30) = -90/59 minutes, which is approximately 1.525 minutes. Therefore, the man's return trip took approximately 1.525 minutes.

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