Question

A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:
A.50 m
B.150 m
C. 200 m
D.Data inadequate

Answer 1

$\huge\boxed{\texttt{\fcolorbox{Red}{aqua}{Hello Friend}}}$

Here is your answer

Let the length of the train is x m
Time = 15 sec.
Speed = Distance/Time
$= \frac{x}{15} m \: per \: sec$

Distance = length of the plate form + length of the train
= x + 100
Time = 25 sec.
Speed = Distance/Time
$= \frac{x + 100}{25} m \: per \: sec$
Now Speed is same so
$\frac{x}{15} = \frac{x + 100}{25} \\ 25x = 15(x + 100) \\ 25x = 15x + 1500 \\ 25x - 15x = 1500 \\ 10x = 1500 \\ x = \frac{1500}{10} \\ x = 150 \: m$
So the length of the train is 150 m

b . 150. is your answer

Hope it helps you