Discussion of Question with ID = 092 under Boats-and-Streams

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Question

A boat can travel 392 km downstream in 28 hours. If it covers the same distance upstream in 98 hours, what is the rate of flow of the stream?

A

5 kmph.

B

6 kmph.

C

4 kmph.

D

8 kmph.

Soln.
Ans: a

The downstream speed = $392/28$ = 14 km/h, and the upstream speed = $392/98$ = 4 km/h. By the shortcut method, the speed of the stream is half of the difference between the downstream and upstream speeds of the boat. So the required speed = ${14 - 4}/2$ = 5 km/h.

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