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SSC CGL 2019 PYQ — Question 31

SSC CGL Tier II Quant - 12/09/2019 • Quantitative Aptitude • Q31

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The speed of a boat in still water is 18 km/hr and the speed of current is 6 km/hr. In how much time (in hours) will a boat travel a distance of 90 km upstream and the same distance downstream?

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Correct answer: B

Explanation

The correct answer is option 2 i.e. 111411\frac{1}{4}.

Boat speed = 18 km/hr

Stream speed = 6 km/hr

Upstream speed = (18 - 6) = 12 km/hr

Downstream speed = (18 + 6) = 24 km/hr

Average speed = (2 × 12 × 24)/(36) = 16 km/hr

Time = 180/16 = 90/8  = 111411\frac{1}{4}