Question

If a man can row 9 km downstream in 45 minutes and the speed of current is 2 kmph then find the speed of boat in still water.

1. 8 kmph
2. 10 kmph
3. 12 kmph
4. 14 kmph

Answer 1

Correct Answer - Option 2 : 10 kmph

Given:

Distance travelled downstream = 9 km

Time taken in travelling downstream = 45 minutes

Speed of current = 2 kmph

Formula used:

Downstream speed = Speed of boat in still water + Speed of current

Calculations:

Downstream speed = 9 km/45 minutes

⇒ 9/(3/4)

⇒ 12 kmph

Speed of boat in still water = Downstream speed – Speed of current

⇒ 12 – 2

⇒ 10 kmph

∴ The speed of boat in still water is 10 kmph