Question

A man can row 6 km hr in still water.it takes him twice as long to row up as to row down the river.

Answer 1

Concept:

Here the concept of speed is used.

i.e. Speed = Distance/ Time

Given:

Speed of a man row = 6 km / hr

Find:

To find the speed of stream.

Solution:

Time of upstream : time of downstream =2:1

As we know that speed is inversely proportional to time with the particular distance and therefore,

speed of upstream : speed of downstream =1:2

Let speed upstream be x

Speed downstream be 2x

Speed in still water =1/2(x+2x)=3x/2

3x/2=6

x=4

Speed of upstream =x=4

Speed of downstream =2x=8

Rate of stream  = 1/2(8−4)

                          =2 km / hr

Hence, the final answer is 2 km/ hr.

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