Question

A train takes $18$ seconds to pas through a platform $162$ m long a $15$ seconds to pass through another platform $120$ m long. The length of the train (in metres) is

• A. $70$
• B. $80$
• C. $90$
• D. $105$

Answer 1

The correct option is C $90$

Let the length of the train be x metres. Then,
Speed of train $=\frac{\text{Length of train + Length of platform}}{\text{Time taken}}$
$\therefore \frac{x+162}{18}=\frac{x+120}{15}$
$\Rightarrow 15x+2430=18x+2160$
$\Rightarrow 3x=270\Rightarrow x=90m$