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 5 seconds. Find the length of the train and its speed. Pick one.
A) 5.6 m/sec B) 15 m/sec C) 18 m/sec D) 9 m/sec E) 25 m/sec
If length of train is l and speed of train is s, then   l/s = 5   (l+180)/s = 20   (l+180)/l = 20/5= 
<gadget id="calculator">20/5</gadget>
<output>4</output>
4   l+180=5*l   4*l=180   l=45 mtrs   s= l/5 = 45/5= 
<gadget id="calculator">45/5</gadget>
<output>9</output>
9 m/sec   ANSWER:9 m/sec
<result>D</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 5 seconds. Find the length of the train and its speed.