Question

A train of length $150metres$takes $10seconds$to pass over another train $100metres$ long coming from opposite direction. If the speed of the first train is $30kmph,$ the speed of the second train is

• A. $72km/h$
• B. $60km/h$
• C. $54km/h$
• D. $48km/h$

Answer 1

The correct option is B

$60km/h$

Speed of the first train$=30km/h$

Let speed of the second train be$xkm/h$

Relative speed$=(30+x)\times (5/18)m/sec$

$=(150+5x)/18$

With this speed train needs to be covered$(150+100)m$ in$10seconds.$

$$\begin{gathered} Speed=\frac{dis\tan ce}{time} \\ 250/10=(150+5x)/18 \\ 25=(150+5x)/18 \\ 450=(150+5x) \\ 300=5x \\ =>x=300/5 \\ =>x=60km/h \end{gathered}$$

Hence, option b is the answer.