The time a passenger train takes to cross another freight train is twice when the passenger train crosses the freight train running in opposite directions. What is the ratio of their speeds?  Choose the correct choice from the following choices:
A) 1:3
B) 3:1
C) 1:4
D) 4:1
E) 1:5
let speed of freight train=x and speed of passenger train=y, and sum of their length =s so time=s/(x-y),when both are in same direction and time=s/(x+y) when oppsite direction.from question,s/(x-y)=2.s/(x+y) so solving this we get, x/y=3/1.= 
<gadget id="calculator">3/1.</gadget>
<output>3</output>
3:1   ANSWER:3:1
<result>B</result>
The time a passenger train takes to cross another freight train is twice when the passenger train crosses the freight train running in opposite directions. What is the ratio of their speeds?