Train P crosses train Q completely in 45 seconds, while running in opposite directions. The lengths of train P and train Q are 1200 metres and 1500 metres, respectively. The speed of train Q is 144 km/h. In how much time can train P cross an 1800-metre long platform?

150 seconds

Formula used :-

Distance = Speed × Time

Speed = \(\frac{Distance}{Time}\)

Total length to be cover = 1200 m + 1500 m = 2700 m

Time taken = 45 seconds

Speed = \(\frac{2700}{45}\) = 60 m/sec

Relative speed of P & Q = 60 m/sec

Speed of Q = 144 km/h = 40 m/sec

Speed of P = 60 - 40 = 20 m /sec

Time taken by train P to cover 1800 m long platform ,

= \(\frac{1200 + 1800 }{20 }\) 

= 150 seconds