An 800-meter-long train can pass a stationary pole completely in 72 seconds. A 1200-meter-long train can also pass a stationary pole completely in 72 seconds. If both the trains are running in the same direction, then the faster train, coming from behind the slower train, can cross the slower train in how much time?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 360 seconds
An 800-meter-long train can pass a stationary pole completely in 72 seconds.
Speed of first train = length of train/time
= 800/72
= 100/9 m/s
A 1200-meter-long train can also pass a stationary pole completely in 72 seconds.
Speed of second train = length of train/time
= 1200/72
= 100/6
= 50/3
Multiply by 3 in the numerator and denominator.
= 150/9 m/s
If both the trains are running in the same direction, then the faster train, coming from behind
the slower train can cross the slower train in 't' seconds.
t = the sum of the length of both trains/speed of the faster train-speed of the slower train
= (800 +1200)/(150/9 - 100/9)
= 2000/(50/9)
2000 × 9/50
= 40 × 9
= 360 seconds