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A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train ?

Answer:

Explanation:

Let the length of the train be $x$ metres and its speed be $y$ m/sec.

Then, $\frac{x}{y}=8$ $\Rightarrow x=8y$

Now, $\frac{x+264}{20}=y$ $\Leftrightarrow 8y+264=20y$

$\Leftrightarrow y=22$.

$\therefore$ Speed $=22$ m/sec $=\left(22\times\frac{18}{5}\right)$ km/hr = 79.2 km/hr.