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A train 150 m long passes a km stone in 15 seconds and another train of the same length travelling in opposite direction in 8 seconds. The speed of the second train is :

Answer:

Explanation:

Speed of first train $=\left(\frac{150}{15}\right)$ m/sec = 10 m/sec.

Let the speed of the second train be $x$ m/sec.

Relative speed $=(10+x)$ m/sec.

$\therefore\frac{300}{10+x}=8$ $\Leftrightarrow 300=80+8x$

$\Leftrightarrow x=\frac{220}{8}$ $=\frac{55}{2}$ m/sec.

So, speed of second train $=\left(\frac{55}{2}\times\frac{18}{5}\right)$ kmph = 99 kmph.