SOLUTION: 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 the

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Question 490906: 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?? how to solve such kinda Q??
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
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?? how to solve such kinda Q??
:
Let a = speed of the faster train
let b = speed of the slower
let the combined length of the trains = 1
write a time equation; time = dist/speed
:
time going the same direction = twice the time going opposite directions
1%2F%28a-b%29 = 2(1%2F%28a%2Bb%29)
which is
1%2F%28a-b%29 = (2%2F%28a%2Bb%29
cross multiply
2(a-b) = a + b
2a - 2b = a + b
2a - a = b + 2b
a = 3b
therefore:
a's speed is 3 time b's speed or 3:1