A train of length 180 m approaches a tunnel of length 620 m. How long will it take the train to pass completely through the tunnel at a speed of 54 km/h?

The correct option is A

53.33 seconds

Speed = $\frac{Distance}{Timetaken}$

Time taken = $\frac{Distance}{Speed}$

Distance to be covered by train to pass through the tunnel = length of the train + length of the platform = 180 m + 620 m = 800 m

Speed of the train = 54 km/h = $\frac{54\times 5}{18}$ m/s = 15 m/s

Time taken for the train to completely pass through the tunnel = $\frac{800}{15}$ = 53.33 seconds