A train crosses a 250 m long platform in 30 seconds and a 220 m long platform in 28 seconds . Find the length of train .

200 m

Let length of train = x meter

Time taken to cross 250 m long platform is 30 sec . so total distance = ( 250 + x ) 

Distance = Speed × Time 

Speed = \(\frac{250 \;+\;x}{30}\)       ------ ( 1 ) 

 Train takes 28 sec to cross a 220 meter long platform, total distance = 220 + x 

 Speed = \(\frac{220\;+\;x}{28}\)      ---------- ( 2 ) 

Speed of train is same so put equation 1 equals to equation 2 

  \(\frac{250 \;+\;x}{30}\) =   \(\frac{220\;+\;x}{28}\)

7000 + 28x = 6600 + 30x 

x = 200

so, length of train = 200 m