A train passes a platform in 40 seconds. The same train passes a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, The length of the platform is  Pick:
A) 280 meter	B) 240 meter	C) 200 meter	D) 300 meter	E) None of these
Explanation:   Speed of the train = 54 km/hr = (54×10)/40 m/s = 15 m/s   Length of the train = speed × time taken to cross the man = 15×20 = 300 m   Let the length of the platform = L   Time taken to cross the platform = (300+L)/15   =&gt; (300+L)/15 = 40   =&gt; 300+L = 15×40 = 600   =&gt; L = 600-300= 
<gadget id="calculator">600-300</gadget>
<output>300</output>
300 meter   Answer: Option 300 meter
<result>D</result>
A train passes a platform in 40 seconds. The same train passes a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, The length of the platform is