Question
A man can row at 5 km/hr in still water. If the velocity
of current is 2 km/hr and it takes him 1 hour to row to a place and come back, how far is the place?Solution
Let the distance be x km. Speed upstream = 5 – 2 = 3 km/hr Speed downstream = 5 + 2 = 7 km/hr ⇒ x/3 + x/7 = 1 ⇒ (7x + 3x)/21 = 1 ⇒ 10x = 21 ⇒ x = 21/10 = 2.1 km
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