A train passes a station platform in 40 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?  Choose the correct choice from the following options:	A) 180 m	B) 200 m	C) 240 m	D) 300 m	E) None
Sol.   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 metres.   Then, x + 300 / 40= 15 ⇔ x + 300 = 600 ⇔ x = 300 m.   Answer 300 m
<result>D</result>
A train passes a station platform in 40 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?