SSC MTS 2022 PYQ — Question 54

The correct answer is Option 1 i.e. 360 km/h.

Time taken by train to cross the pole = 20 sec

Time taken by the train to cross the bridge = 32 sec

Length of bridge = 1200 m

Distance = Speed × time

Let the length of the train = x meters

If it crosses the stationary pole in 20 seconds, thus the speed of the train = $Length \over time$= $x \over 20$

If it crosses the bridge in 32 seconds, then the speed of the train would be = $(x + 1200)\over 32$

Therefore, $x \over 20$ = $(x + 1200)\over 32$

⇒ 8x = 5x + 6000

⇒ 3x = 6000 

⇒ x = 2000 metres

Thus, the speed of the train = $2000 \over 20$ = 100 metres/s

In km/h, 100 × $18 \over 5$ =  360 km/h

Hence the speed of the train is 360 km/h.