Multiple choice

A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes.How long will it take to go 5 km in stationary water? एक नाविक धारा के विपरीत 2 किमी 1 घण्टे में जाता है और धारा के ओर 1 किमी 10 मिनट में जाता है, तो शान्त जल में 5 किमी. जाने में कितना समय लगेगा?

  1. 40 minute/मिनट

  2. 1 hours 15 min/1घंटे 15 मिनट

  3. 1 hours/ 1घंटे

  4. 1 hours 30 min/1 घंटे 30 मिनट
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Against current: speed = 2 km in 1 hr = 2 km/hr. This is boat speed - current speed. Along current: speed = 1 km in 10 min = 6 km/hr. This is boat speed + current speed. Adding both equations: 2(boat speed) = 8 km/hr, so boat speed = 4 km/hr in still water. Time for 5 km = 5/4 hr = 1.25 hours = 1 hr 15 min.

Keep practicing — related questions