Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 10 sec. What is the length of the fast train?	Choose the most appropriate option.
A) 55 7/6 m	B) 55 7/4 m	C) 55 7/2 m	D) 55 7/9 m	E) 55 5/9 m
Relative speed = (40 - 20)= 
<gadget id="calculator">(40 - 20)</gadget>
<output>20</output>
20 km/hr.= 20 * 5/ 18 = 50/9 m/sec.   Length of faster train = 50/9 * 10 = 500/9 = 55 5/9 m.Answer:55 5/9 m
<result>E</result>
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 10 sec. What is the length of the fast train?