A train P going at the speed of 70 km/h completely passes train Q of length 170 m, going in the same direction on parallel tracks, at 56 km/h, in minutes. How much time (in seconds) will P take to cross completely train R of length 220 m, going at 74 km/h in the opposite direction?

Question

Question

This question was previously asked in

RRB Group D 1 Sept 2022 Shift 2 Official Paper

Answer 1

Given:

Speed of the faster train (Q) = 56 kmph

Speed of the slower train (P) = 70 kmph

Speed of the slower train (R) = 74 kmph

Length of the train Q = 170m

Length of the train R = 220m

Concept used:

While going in the same direction, the relative speed of two objects is the difference between their individual speeds.

Speed × Time = Distance

Calculation:

let the length of train P be x.

3/2 minutes = 90 seconds

⇒ 90 = (x + 170)/(70 - 56) × (5/18)

⇒ 350 = x + 170

x = 180 m

Now time taken by P to cross R:

Time = (180 + 220)/(70 + 74) × (5/18)

Time = 400/40 = 10 seconds.

The answer is 10 seconds.

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