A 1 km long train travelling at a speed of 60km/h enter a tunnel 1km long. What time will the train take to come out of the tunnel fully.

2 minutes

Step-by-step explanation:

The front of the train enters the tunnel and travels 1 km before the rear of the train enters the tunnel.  Thus, the total distance traveled by the front of the train is 2 km, and this is covered in a certain number of hours:

Since distance = rate times time, time = distance / rate.  In this particular case we have:

                                              2 km

time = distance / rate = = (1/30) hr

                                           60 km/hr

(1/30) hr converts to 2 minutes, since 1 hr = 60 minutes