Multiple choice

If the sum of upstream and downstream speed is 36 km/hr and the speed of the current is 3km/hr. Then find time taken to cover 52.5 km in downward ?

  1. 1.5 hr

  2. 3.25 hr

  3. 2.5 hr

  4. 2 hr
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The sum of upstream and downstream speeds equals twice the boat's speed in still water (since (b-c)+(b+c)=2b). So boat speed = 36/2 = 18 km/hr. Downstream speed = 18+3 = 21 km/hr. Time = distance/speed = 52.5/21 = 2.5 hours.

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