Question

A train $100$ metres long moving at a speed of $50km/hr$ crosses a train $120$ metres long coming from opposite direction in $6$ seconds. The speed of the second train is

• A. $132km/hr$
• B. $82km/hr$
• C. $60km/hr$
• D. $50km/hr$

Answer 1

The correct option is B $82km/hr$

Let the speed of the second train be $xkm/hr$.
Relative speed $=(x+50)km/hr$
$=[(x+50)\times \frac{5}{18}]m/sec=\left(\frac{250+5x}{18}\right)m/sec$
Distance covered $=100+120=220m$
$\frac{220}{\frac{250+5x}{18}}=6$
$\Rightarrow 250+5x=\frac{220+18}{6}$
$\Rightarrow 250+5x=660$
$\Rightarrow x=82km/hr$