Mathematics · solved example
A boat goes 20 km downstream in 2 hours and returns the same distance upstream in 4 hours. Find the speed of the boat in still water.
- 8
- 6.5
- 7.5Correct
- 7
Solution
Downstream speed is 20/2 = 10 km/h and upstream 20/4 = 5 km/h. Still-water speed is their average: (10 + 5)/2 = 7.5 km/h.