150 m long train crossed a person standing on platform in 9 seconds.…

When a train cross a man then the distance traveled by train is equals to length of train.

Now,

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

Distance = length of train = 150m

Time = 9 sec

Speed of train = \(\frac{150}{9}\) m/sec

                       = \(\frac{50}{3}\) m/sec

                       = \(\frac{50}{3}\) × \(\frac{18}{5}\) km/hr

                       = 60 km/hr