A train consists of 12 boggies, each boggy 15 metres long. The train crosses a telegraph post in 18 seconds. Due to some problem, one boggies were detached. The train now crosses a telegraph post in Choices.
A) 16.5 sec  B) 12 sec  C) 15 sec  D) 20 sec  E) None of these
Length of train = 12 Ã— 15 = 180 m.   Then, speed of train = 180â„18 = 10 m/s   Now, length of train = 11 Ã— 15 = 165m   âˆ´ Required time = 165â„10 = 16.5 sec.   16.5 secnswer 16.5 sec
<result>A</result>
A train consists of 12 boggies, each boggy 15 metres long. The train crosses a telegraph post in 18 seconds. Due to some problem, one boggies were detached. The train now crosses a telegraph post in