A train, 800-meter-long is running with a speed of 78 km/hr. It crosses a tunnel in 1 minute. What is the length of the tunnel?
650 meter
555 meter
500 meter
458 meter
Explanation:
Let length of tunnel is x meter.
Distance = 800 + x meter
Time = 1 minute = 60 seconds
Speed = 78 km/hr. = 78 $\times$ 5/18 m/s = 65/3 m/s
Distance = Speed $\times$ Time
=> 800 + x = 65/3 $\times$ 60
=> 800 + x = 20 $\times$ 65=1300
=> x = 1300 - 800 = 500.