A train consists of 12 boggies, each boggy 15 metres long. The train crosses a telegraph post in 18 seconds. Due to some problem, three boggies were detached. The train now crosses a telegraph post in
Choose the correct option
A) 18 sec B) 12 sec C) 15 sec D) 20 sec E) 13.5 sec
Length of train = 12 Ã— 15 = 180 m.   Then, speed of train = 180â„18 = 10 m/s   Now, length of train = 9 Ã— 15 = 135m   âˆ´ Required time = 135â„10 = 13.5 sec.   Answer 13.5 sec
<result>E</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, three boggies were detached. The train now crosses a telegraph post in