A man is standing on a railway bridge which is 180 m long. He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. Find the length of the train and its speed.	Choose the correct choice from the following answers:
A) 36	B) 54	C) 67	D) 76	E) None
Sol.   Let the length of the train be x metres.   Then, the train covers x metres in 8 seconds and (x + 180) metres in 20 seconds.   ∴ x/8 = x + 180 / 20 ⇔ 20x = 8(x + 180) ⇔ x = 120.   ∴ Length of the train = 120 m.   Speed of the train = [120/8]m/sec = m/sec = [15 * 18/5= 
<gadget id="calculator">15 * 18/5</gadget>
<output>54</output>
54 kmph.   Answer 54
<result>B</result>
A man is standing on a railway bridge which is 180 m long. He finds that a train crosses the bridge in 20 seconds but himself in 8 seconds. Find the length of the train and its speed.