Two trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 4 hours and 36 hours respectively. The ratio of their speeds is?	Choose the correct choice from the following answers:
A) 4:9
B) 4:3
C) 4:5
D) 3:1
E) 4:2
Let us name the trains A and B.   Then, (A's speed) : (B's speed)   = √b : √a = √36 : √4   = 6:2 = 3:1   Answer:3:1
<result>D</result>
Two trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 4 hours and 36 hours respectively. The ratio of their speeds is?