Discussion of Question with ID = 082 under Boats-and-Streams

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Question

A boat can travel 300 km downstream in 30 hours. If it covers the same distance upstream in 50 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 = $300/30$ = 10 km/h, and the upstream speed = $300/50$ = 6 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 = ${10 + 6}/2$ = 8 km/h.


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