Two trains running in opposite directions cross a man standing on the platform in 47 seconds and 38 seconds respectively and they cross each other in 40 seconds. The ratio of their speeds is:
Choices:
A) 3 : 1
B) 3 : 2
C) 2 : 7
D) 3 : 25
E) 3 : 4
Let the speeds of the two trains be x m/sec and y m/sec respectively. Then, length of the first train = 47 x meters, and length of the second train = 38 y meters. (47 x + 37 y) / (x + y) = 40 ==&gt;   47 x + 38 y = 40x + 40 y ==&gt; 7x = 2 y ==&gt; x/y = 2/7   Answer: Option 2 : 7
<result>C</result>
Two trains running in opposite directions cross a man standing on the platform in 47 seconds and 38 seconds respectively and they cross each other in 40 seconds. The ratio of their speeds is: