Two trains, one from P to Q and the other from Q to P, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 36 hours respectively. The ratio of their speeds is Choose the correct option.
A) 4:1  B) 4:2  C) 4:5  D) 6:3  E) 3:6
Ratio of their speeds = Speed of first train : Speed of second train   = √36−−√9   = 6:3   Answer is 6:3.
<result>D</result>
Two trains, one from P to Q and the other from Q to P, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 36 hours respectively. The ratio of their speeds is