Question

A motorboat when moving downstream covers the distance between two cities in 4 hours, while it covers the same distance upstream in 5 hours. If the speed of the river is 2km/h, find the speed of the motorboat in still water.

Answer 1

Define x:

Speed of the river = 2kmh (Given)

Let the speed of the motorboat in still water be x km/h

Upstream:

Speed = ( x - 2) km/h

Distance = Time x Speed

Distance = 5(x - 2) = 5x - 10 km

Downstream:

Speed = (x + 2) km/h

Distance = Time x Speed

Distance = 4(x + 2) = 4x + 8 km

Solve x:

Given that the distance traveled upstream and downstream are the same.

5x - 10 = 4x + 8

x = 18 km/h

Answer: The speed of the motorboat in still water is 18 km/h