Question

A red train and a blue train are running parallel to each other in the same direction. If the red train is faster than the blue train by 30 km/h and both trains are 500 m long, how long will it take the red train to overtake the blue train completely?

• A. 1 min
• B. 2 min
• C. 5 min
• D. 10 min

Answer 1

The correct option is B 2 min

Picturing the faster train overtaking the slower one, we find:


For the red train to completely overtake the blue train, point D has to cross point A.

Hence,

$Distancetobecovered=500m+500m=1000m=1km$

$Differencebetweenthespeedofthetrains=30km/h$

$Time=\frac{Distance}{Speed}=\frac{1}{30}hours=60\times \frac{1}{30}min=2min$