Question 607707: Train A and B are traveling in the same direction,on parallel tracks. Train A is traveling at 100 miles per hour ans train B is traveling at 120 miles per hour.Train A passes a station at 8:10 P.M. If train B passes the same station at 8:22 P.M., at what time will train B catch up to train A?
Found 2 solutions by Nihal@SriLanka, Alan3354:
Answer by Nihal@SriLanka(22)   (Show Source):
You can put this solution on YOUR website! Imagine two runners in a race on parallel tracks. Suppose that sometime after they begin the race the distance between them is one foot. If from this point onwards both runners maintain equal speeds what will be the distance that separates them. One feet of course. Now suppose the runner behind cannot maintain his speed and reduces his speed what will happen. He/she will start drifting further and further apart from the runner ahead as the race progresses. If on the other hand the runner behind is able to muster enough energy to move at a higher speed than the runner ahead he/she will start catching up with the runner ahead and if the race continues long enough, pass the runner ahead. What is important to note here is that the runner behind is catching up on the distance between the two (one foot in this case) at a speed which is the difference of speeds between the runners.
In the given example Train B has to catch up the distance between the two trains at a speed of (120-100) miles per hour. By 8.22 P.M. Train A had had 12 minutes traveling time, in which time it is able to move 100 * 12/60 (i.e. 20 ) miles past the station, which is the distance between the trains when train B starts to catch up with train A. Hence train B will catch up with train A 20 /20 hours after 8.22 P.M. i.e. at 9.22 P.M..
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Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! Train A and B are traveling in the same direction,on parallel tracks. Train A is traveling at 100 miles per hour ans train B is traveling at 120 miles per hour.Train A passes a station at 8:10 P.M. If train B passes the same station at 8:22 P.M., at what time will train B catch up to train A?
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In the 12 minutes from 810 to 822, Train A is (12/60)*100 miles ahead
= 20 miles.
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Train B passes the station at 822, Train A is 20 miles ahead.
Train B gains on Train A at 20 mile/hr (100 - 80)
20/20 = 1 hour
822 + 1 = 9:22
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