Question

A person rows x km downstream and the same distance upstream in 10 hours. He can row 2x km downstream in 5 hours. What is the time taken to row x km upstream?

A 12 hrs Correct Answer Incorrect Answer
B 14 hrs Correct Answer Incorrect Answer
C 18 hrs Correct Answer Incorrect Answer
D 7.5 hrs Correct Answer Incorrect Answer

Solution

Let the downstream speed of the boat be ‘a’ km/hr According to the question, (2x/a) = 5 Or, (x/a) = (5/2) Or, (x/a) = 2.5 = time taken to travel ‘x’ km downstream Let the upstream speed of the boat be ‘b’ km/hr Also, (x/a) + (x/b) = 10 Or, 2.5 + (x/b) = 10 Or, (x/b) = 7.5 hours

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