Question

A boat takes 3 days to travel from town A to town B, but it takes 4 days to travel from town B to town A. If a motor-less raft is left alone in the water by town A, how long will it take for the raft to float to town B?

Answer 1

24 days

Explanation:

The distance from A to B equals the distance from B to A.

Let the distance between A and B be d.

3 days = 72 hours

4 days = 96 hours

speed = distance/time

speeds are in miles per hour

speed from A to B = d/72

speed from B to A = d/96

difference in speeds:

d/72 - d/96 = d/288

The speed of the water is half of the difference.

speed = d/576

When the raft floats from A to B, it uses only the speed of the water.

d/576 / d/72 = 1/8

The speed of the water is 1/8 the overall speed of the trip from A to B, so traveling by the speed of the water alone must take 8 times longer than with the boat motor.

8 * 3 days = 24 days