A train passes a station platform in 39 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) 276 m
B) 279 m
C) 240 m
D) 207 m
E) 285 m
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 / 39= 15   x + 300 = 585   x =285m.   Answer: 285 m
<result>E</result>
A train passes a station platform in 39 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?