Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively . If they cross each other in 21 seconds, what is the ratio of their speeds?
Choose the most appropriate option:	A) 1:3	B) 3:1	C) 2:3	D) 3:2	E) 3:4
Let the speed of the trains be x and y respectively   length of train1 = 27x   length of train2 = 17y   Relative speed= x+ y   Time taken to cross each other = 21 s   = (27x + 17 y)/(x+y) = 21   = (27x + 17 y)/ = 21(x+y)   = 6x = 4y   =x/y = 4/6 = 2/3 i.e 2:3   Answer :2:3
<result>C</result>
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively . If they cross each other in 21 seconds, what is the ratio of their speeds?