#4 Problems on Trains

A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train ?

A) 69.5 km/hr B) 70 km/hr C) 79 km/hr D) 79.2 km/hr

Answer: D) 79.2 km/hr 

Explanation:

Let the length of the train be x metres and its speed by y m/sec.
Then,
Now,  
8y + 264 = 20y
y = 22.
Speed = 22 m/sec =km/hr = 79.2 km/hr.