Question

A man can row at 5 km/h in still water. He rows upstream 3 km and then returns to his starting point. If the total time taken is 1 h 15 m, find the speed of the stream.
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Answer 1

Answer:

Assume that a man can row at the speed of x km/hr in still water and he rows the same distance up and down in a stream which flows at a rate of y km/hr. Then his average speed throughout the journey

=Speed downstream × Speed downstream

Speed in still water

=(x+y)(x−y)x km/hr

= Speed downstream × Speed downstreamSpeed in still water

=(x+y)(x−y)x km/hr

Speed of the man in still water = 12 km/hr

Speed of the stream = 3 km/hr

Speed downstream = (12+3) = 15 km/hr

Speed upstream = (12-3) = 9 km/hr

Average Speed =

Average Speed = Speed downstream × Speed downstream

Average Speed = Speed downstream × Speed downstreamSpeed in still water

=15×9=12

=15×3/4

=45/4

=11 (1/4) km/hr

Step-by-step explanation:

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