Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is: Select.
A) 1 : 3  B) 3 : 2  C) 3 : 4  D) 2 : 1  E) None of these
Let the speeds of the two trains be S1 m/sec and S2 m/sec respectively. Then, length of the first train = 27S1 metres, and length of the second train = 17S2 metres.   ∴ 27S1+17S2/S1+S2=23 ⇒ 27S1 + 17S2 = 23S1 + 23S2   ⇒ 4S1 = 6S2 ⇒ S1⁄S2 = 3⁄2   Answer 3 : 2
<result>B</result>
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is: