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Two trains, Train A and Train B, simultaneously depart Station A and Station B. Station A and Station B are 252.5 miles apart from each other. Train A is moving at 124.7mph towards Station B, and Train B is moving at 253.5mph towards Station A. If both trains departed at 10:00AM and it is now 10:08, how much longer until both trains pass each other?

 Mar 29, 2016
 #1
avatar+817 
+5

Train A

124.7mph (124.7/60*8)=16.162mi

124.7mph/60mins*8(mins)

 

Train B

253mph (253/60*8)=33.7mi

33.7+16.16=49.89mi

 

252.5-49.89=203.61mi (left to travel)

 

124.7+252.5=377.2mph (combined speed)

 

203.61mi / 377.2mph =.539hrs (time to come together)

 

so 32 mins, so 10:08+32mins= 10:40

 Mar 29, 2016
 #2
avatar+129907 
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Very nice, Landry......here's another approach

 

The combined rates  = 377.2

 

And the total distance to cover = 252.5 miles   .......so.....

 

Distance / Rate   = Total Time for the trip in hours .....    and we have

 

252.5 / 377.2  = about .668 hrs

 

And in minutes this is about   .668 x 60   =  40 minutes

 

And....since they have already traveled 8 minutes, they have 32 more to travel .........so  they will meet at 10:40..........as Landry found

 

 

cool cool cool

 Mar 29, 2016
 #3
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Thanks!Thanks.

 Mar 30, 2016
 #4
avatar+129907 
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I just realized that the combined rate we gave was in error....it should have been 378.2....so.....

 

The total time they take from the time they start until the time they meet  [in minutes] is given by

 

[252.5/378.2] * 60  = about 40.058 minutes.....and since they have traveled 8 minutes already......they will meet in 32.058 minutes

 

This is still close enough to our previous answer of ≈ 32 minutes

 

 

cool cool cool

 Mar 30, 2016
 #5
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the answer is 32.058 minutes

 Jan 20, 2017

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