Question

A man can row 5 km/hr in still water. If the speed of the current is 2 km/hr, it takes 4 hours more in upstream than in the downstream for the same distance. Find the distance.

A 30 km Correct Answer Incorrect Answer
B 21 km Correct Answer Incorrect Answer
C 10 km Correct Answer Incorrect Answer
D 24 km Correct Answer Incorrect Answer
E None of these Correct Answer Incorrect Answer

Solution

Speed of man in still water = x = 5 km/hr Speed of current = y = 2 km/hr Let the distance be x km. Now according to the question, Upstream time = Downstream time + 4 => x/(5-2) – x/(5+2) = 4 => x/3 – x/7 = 4 => [(7x - 3x)/21] = 4 => x = 21 km

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