A train passes a station platform in 42 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform? Choices:  A) 123  B) 166  C) 240  D) 157  E) 330
Speed = [54 * 5/18] m/sec = 15 m/sec.   Length of the train = (15 * 20)= 
<gadget id="calculator">(15 * 20)</gadget>
<output>300</output>
300 m.   Let the length of the platform be x meters.   Then, (x + 300) / 42= 15   x + 300 = 630   x = 330 m.   Answer: 330
<result>E</result>
A train passes a station platform in 42 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?