Question

Two trains, $100$ and $140$ metres long are going in the same direction. The faster train takes $2$ minutes to pass the other completely. If they are moving in opposite directions, then they pass each other completely in $5$ seconds. What is the speed (in m/sec) of the faster train?

• A. $48$
• B. $25$
• C. $34$
• D. $68$

Answer 1

The correct option is B $25$

Let the speed of faster and slower trains be $x$ m/sec and $y$ m/sec respectively. Then,
$\frac{240}{x-y}=120$
$\Rightarrow x-y=2\cdots \left(i\right)$
And $\frac{240}{x+y}=5$
$\Rightarrow x+y=48\cdots \left(ii\right)$

Adding $\left(i\right)$ and $\left(ii\right),$ we get
$2x=50$
$\Rightarrow x=25$
Putting $x=25$ in equation $\left(i\right),$ we get $y=23$
Hence, speed of faster train $=25$ m/sec.