A motorboat that normally travels at 8 km/h in still water heads directly across a 6-km/h flowing river. The resulting speed of the boat is about
A)6 km/h.
B)8 km/h.
C)10 km/h.
D)20 km/h.

Question

Quizplus · Accepted Answer

When the motorboat travels across a river flowing at 6 km/h, the boat's speed with respect to the river is 8 - 6 = 2 km/h. Therefore, the boat will take 6/2 = 3 hours to cross the river. During this time, the boat will travel a distance of 8 x 3 = 24 km (distance = speed x time). Hence, the resulting speed of the boat is 24/3 = 8 km/h (total distance / total time).

A Motorboat That Normally Travels at 8 Km/h in Still