Question
A man rows a certain distance downstream in 5 hours and
back to the same point in 8 hours. If the speed of the stream is 4.5 km/hr then what is the speed of the man in still water?Solution
Let the speed of the man in still water be x km/hr. Downstream speed = (x+ 4.5) km/hr. Upstream speed = (x- 4.5) km/hr. (x+ 4.5) × 5 = (x- 4.5) × 8 5 x + 22.5 = 8 x - 36 3 x = 58.5 ∴ x = 19.5 km/hr.
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