A man can row at 7 km/hour in still water. He finds that it takes twice the time to row upstream than the time to row downstream. The speed of the stream is
Correct Answer: Option C
The speed of the stream is y km/hour (say)
Hence upstream speed will be (7-y) km/hour
And downstream speed will be (7+y)km/hour
it takes twice the time to row upstream than the time to row downstream. Hence, speed of downstream is twice than the speed of upstream.
According to the problem, 7+y = 2(7-y)
⇒7+y = 14 – 2y
⇒3y = 7
⇒y = 2.33
Speed of the stream = 2.33 km/hour
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