Question 203553: I need help solving:
An express train and a local train both leave Gray's Lake at 12:00 noon and head for Chicago 60 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of it. Find the speed of each train.
Answer by promotion analysis(5)   (Show Source):
You can put this solution on YOUR website! This one is solved by using the formula time = distance / velocity.
Let the velocity of the express train be v miles per hour.
The time taken for the express train to complete the journey (call it t1)
t1 = 60/v
Now, we know that the speed of the local train is HALF that of the express train (ie equals 0.5v), so we can use the same formula to calculate the time (call it t2) it takes the local train to complete the journey
t2 = 60 / (0.5v) = 120/v
The difference in times is two hours
t2 - t1 = 2 (its t2 minus t1 because t2 is the longer time)
(120 - 60)/v = 2 (substituting)
60/v = 2
v = 30 mph
So the express train goes at 30mph and therefore travels the 60 miles in 2 hours
The local train goes at 15mph and therefore takes 4 hours, ie two hours longer.
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