A gun is fired from behind a train and the driver hears the sound 1 min 30 sec later than the guard. Find the length of train if the speed of train and sound are 60 km/hr and 1100 m/min .

150 m

Speed of train = 60 km/hr = 1000 m/min 

Speed of sound = 1100 m/min 

As train and bullet both moves in same direction .

So, relative speed  = ( 1100 - 1000 ) = 100 m/min 

Time taken by sound to travel through the length of train = 1 min 30 sec 

= \(\frac{3}{2}\) min 

Distance = Speed × Time 

             =   100 × \(\frac{3}{2}\)  = 150 m 

So , length of train = 150 m