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SSC GD 2023 PYQ — Question 57

SSC GD Constable (English) - 16 Jan 2023 - Shift 1 • Quantitative Aptitude • Q57

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A man rows upstream 15 km and downstream 18 km, he takes 3 hours each time. The speed of the current is:

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Correct answer: A

Explanation

The correct answer is option 1 i.e. 12 {1 \over 2} km/h.

Let's assume the speed of the man is x and the speed of the current is y.

Downstream speed = x  + y

Upsream speed = x - y

According to the question

15/3 =  x - y

x - y = 5 ..........1

and 

18/3 = x + y

x + y = 6..............2

So, the speed of the stream from equations 1 and 2.

y = 1/2 km/h