A train passes a station platform in 55 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:
A) 180 m
B) 525 m
C) 240 m
D) 320 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 / 55= 15 ⇔ x + 300 = 825 ⇔ x = 525 m.   Answer 525 m
<result>B</result>
A train passes a station platform in 55 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?