The speed of a stream is 4 km/h. A boat can travel 6 km upstream in the same time it takes to travel 12 km downstream.

Question

Find the speed of the boat in still water.

Answer 1

6/(4-b)= 12/(4+b)

24+6b= 48-12b

18b = 24

b= 4/3 km/hr

= boat speed in still water

= 1 1/3 km/hr

= 1.333... km/hr

2 1/4 hours each way

5 1/3 km/hr downstream

2 2/3 km/hr upstream