Question

A boat can travel 35km upstream in 7hours. The speed of the stream is 20kmph. Find the time taken by boat to travel 20km upstream and 45km downstream.

1. 6 hours
2. 3 hours
3. 2 hours
4. 7 hours
5. 5 hours

Answer 1

Correct Answer - Option 5 : 5 hours

Given:

⇒ Speed upstream = 35/7 = 5kmph

⇒ Speed of stream = 20kmph

⇒ Speed of boat in still water = 20 + 5 = 25 kmph

⇒ Speed downstream = 25 + 20 = 45 kmph

∴ Required time = 45/45 + 20/5 = 5 hours