Question

It takes a boat five hours to travel upstream. It takes the same boat for hours to travel the same distance downstream. If the current is 1 mph, what is the speed of the boat in Stillwater?

Answer 1

0.11 kmph

Explanation:

Let distance be LCM(5,4,1) = 20 km

Upstream speed (US) = 20/5 = 4 kmph

Downstream speed (DS) = 20/4 = 5 kmph

Speed of boat = (DS + US)/2 = (5+4)/2 = 4.5

Speed of current = (US - DS)/2 = (5-4)/2 = 0.5

= 0.5 kmph.

If Boat speed= 4.5, river speed = 0.5 kmph

If Boat speed= 1, river speed = 0.5/4.5 x 1 = 0.11 kmph