Discussion of Question with ID = 042 under Boats-and-Streams

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Question

A boat can travel 288 km downstream in 24 hours. If it covers the same distance upstream in 72 hours, what is the speed of the boat in still water?

A

8 kmph.

B

9 kmph.

C

7 kmph.

D

11 kmph.

Soln.
Ans: a

The downstream speed = $288/24$ = 12 km/h, and the upstream speed = $288/72$ = 4 km/h. By the shortcut method, the speed of the boat in still water is average of the downstream and upstream speeds of the boat. So the required speed = ${12 + 4}/2$ = 8 km/h.


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