Multiple choice

A boat running downstream takes 4 hrs to go to a place. In what time will it come to the same place if the ratio of speed of boat in still water and that of stream is 5:3?

  1. 15 hrs

  2. 10 hrs

  3. 08 hrs

  4. 12 hrs

  5. 16 hrs
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Boat speed:stream speed=5:3, so let B=5k, S=3k. Downstream speed=B+S=8k takes 4 hours. Upstream speed=B-S=2k will take (8k/2k)×4=16 hours (same distance, inverse ratio of speeds). This elegantly uses the concept that time is inversely proportional to speed for constant distance. The answer 16 hours matches option E.

Keep practicing — related questions