A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute then the length of the tunnel (in meters) is
130
360
500
540
Explanation:
| Speed =$ \left(78 \times\dfrac{5}{18} \right) $m/sec=$ \left(\dfrac{65}{3} \right) $m/sec. |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be $ x $ metres.
| Then,$ \left(\dfrac{800 + x}{60} \right) $=$ \dfrac{65}{3} $ |
$\Rightarrow 3\left(800 + x \right)$ = 3900
$\Rightarrow x $ = 500.