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 81 hours and 9 hours respectively. The ratio of their speeds is	Select the correct option.
A) 1 : 2 B) 2 : 3 C) 1 : 3 D) 4 : 5 E) None
Sol.   Let us name the trains as A and B. Then,   (A's speed) : (B's speed) = √b : √a   = √9 : √81   = 3 : 9. =&gt; 1 : 3   Answer 1 : 3
<result>C</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 81 hours and 9 hours respectively. The ratio of their speeds is