A man rows down a river 15 km in 3 hrs. with the stream and returns in $$7\frac{1}{2}$$, The rate at which he rows in still water is
speed of man = x
speed of stream = y
he rows down the river 15 km in 3 hrs, i.e; x+y = 15/3 = 5kmph -------(1)
and he took 7.5hrs during upstream
i,e; x-y = 15/7.5 = 2kmph-------(2)
on solving (1) and (2)
x+y=5
x-y=2
x = 3.5kmph
so the answer is option C.
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