Question 631024: The MRT leaves a station and travels at forty-five miles an hour. Three hours later, a second train leaves and travels at seventy-five miles an hour. How long will it take the second train to overtake the first? Answer by htmentor(807) (Show Source):
You can put this solution on YOUR website! The 1st train has a head start of 45 mph * 3 h = 135 mi
The relative speed of the two trains = 75 mph - 45 mph = 30 mph
So it is as if the 1st train is standing still and the 2nd train approaches at 30 mph.
So the total time will be 135 mi/30 mph = 4.5 hours