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SSC GD 2021 PYQ — Question 55

SSC GD Constable (English) - 18th November 2021 Shift 1 • Quantitative Aptitude • Q55

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The distance between two stations A and B is 700 km. A train covers the journey from A to B at a speed of 80 km/h and returns back to A with a uniform speed of 65 km/h. The average of train during the whole journey, is closest to:

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Correct answer: B

Explanation

The correct answer is option 2 i.e. 71.72km/h

The distance between A and B = 700 km

Average speed = total distance/total time

Time taken from A to B = 700/80 = 35/4 

Time taken from B to A = 700/65 = 140/13

Average speed = 1400354×14013\dfrac{1400}{\frac{35}{4}\times\frac{140}{13}} = 71.72 km/h