Question

A motorboat takes 4 hours to travel 128 km going upstream. The return trip takes 2

hours going downstream. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

Explanation:

Rate × time = distance

If x is the rate of the boat and y is the rate of the water:

(x − y) × 4 = 128

(x + y) × 2 = 128

Simplifying:

x − y = 32

x + y = 64

Solve with elimination (add the equations together):

2x = 96

x = 48

y = 16

The speed of the boat is 48 km/hr and the speed of the water is 16 km/hr.