Question

# Rohit can row downstream 32 km in 4 hours and upstream 4km in 1 hour. Find his speed in still water and the speed of the current.

A

6 km/hr, 2 km/hr

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B

4 km/hr, 4 km/hr

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C

20 km/hr, 4 km/hr

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D

4 km/hr, 2 km/hr

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Solution

## The correct option is A 6 km/hr, 2 km/hr Let speed of Rohit rowing in still water = x km/hr and speed of current = y km/hr. Then, Speed downstream = (x + y) km/hr Speed upstream = (x - y) km / hr We know that, Time=DistanceSpeed 4=32x+y and 1=4x−y ⇒ x+y=8 ⋯(1) ⇒x−y=4 ⋯(2) On adding (1) and (2), we get 2x = 12 ⇒ x = 6 On substituiting x = 6 in (1), we get 6 + y = 8 ⇒ y = 2 ∴ The rowing speed in still water is 6 km/hr and the speed of current is 2 km/hr.

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