Question

A 100 m long train running at a speed of 48 km/hr passes a tunnel in 21 seconds. Find the length of the tunnel. (Use rule of three method that i.e proportional method). [6]

Answer 1

Answer:

Length of train = 100 m

Speed of train = 48km/h = (48×5)/18 m/s

time taken = (100×18)/48×5 = 15/2 sec

That means, In 15/2 sec, train covers distance = 100 m

or, In 1 sec, train covers distance = (100×2)/15 m = 40/3 m

or, In 21 sec,train covers distance = (40×21)/3 m = 280 m

Hence, length of tunnel = (280-100) m = 180 m.