Question
A man can row 32 km/hr in still water. It takes him
thrice as long to row up as to row down the river. Find the rate of the current.Solution
Let man’s rate upstream be x kmph. Then his rate downstream = 3x kmph. ∴Rate in still water =1/2 (3x+x)kmph=2x kmph ⇒32 = 2x⇒x = 16⇒3x=48 ∴ Rate of the stream =1/2 (48-16)kmph=16 kmph Alternate Method: Let U = speed of man in still water & V = speed of water So here N = time of upstream/ time of downstream = 3 So U/V = (N+1)/(N-1) = (3+1)/(3-1) = 4/2 =2 V = 32/2 = 16kmph
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