Question

A 500m long train took 33sec to pass a bridge 160m long .find the speed of the train in km/hr?

Answer 1

total distance travelled by train = length of the train + length of bridge 
                                             = 500 + 160  = 660m
speed = distance/time
          = 660/33
          = 20m/s.
speed = 20*3600/1000 Km/hr  (1m = 1/1000 Km.     1s = 1/3600 hr.)
          = 72Km./hr.

Answer 2

Length of train = 500mLength of bridge= 160mtotal length to be covered = 500m + 160m = 660mtime taken = 33secSpeed in m/sec = 660/33 = 20 m/secSpeed in km/hr = 72 km / hr