A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively...........

Explanation:

Let the length of the train be x metres and its speed by y m/sec.
Then, x/y = 8 => x = 8y
Now, (x+264)/20 = y
8y + 264 = 20y
y = 22.
Speed = 22 m/sec = (22*18/5) km/hr = 79.2 km/hr.

Hence, option 1 is the correct answer.