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SSC Selection Post 2019 PYQ — Question 61

SSC Selection Post - Matriculation Level 2019 - 14 Oct 2019 - Shift 1 • Quantitative Aptitude • Q61

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A train X running at 72 km/h crosses another train Y running at 54 km/h in opposite direction in 15 seconds. If the length of Y is two-fifth that of X, then what is the length (in meter) of X?

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Correct answer: A

Explanation

The correct answer is Option 1 i.e. 375.

Let length of Train X = x  meters
Then, length of Train Y = (2/5) x

Relative speed (opposite direction) = 72 + 54 = 126 km/h =(126 × 1000)/3600 = 35 m/s

Total length =x+25x=7x5= x + \frac{2}{5}x = \frac{7x}{5} \\

Time = 15 sec, so:

7x5=35×15=525x=525×57\frac{7x}{5} = 35 \times 15 = 525 \\ x = \frac{525 \times 5}{7}

x = 375 m