Question

Two trains running in opposite directions at $36kmph$ and $45kmph$ cross each other in $20$ seconds. If one train is $200m$ long, the length of the other train is :

• A. $144m$
• B. $200m$
• C. $240m$
• D. $250m$

Answer 1

The correct option is D $250m$

Let the length of the other train be $xm.$

Sum of their lengths $=(200+x)m$

Relative speed $=(36+45)kmph=81kmph=(81\times \frac{5}{18})=\frac{45}{2}m/sec$

$\frac{200+x}{\frac{45}{2}}=20$

$2x=500$

$x=250$

Therefore, the length of the other train is $250m.$