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A train leaves New York for Boston, 200 miles away, at 3:00 P.M. and averages 65 mph. Another train leaves Boston for New York on an adjacent set of tracks at 5:00 P.M. and averages 70 mph. At what time will the trains meet?

2006-10-09 15:35:43 · 6 answers · asked by puffer fish 5 in Education & Reference Homework Help

6 answers

First off ask yourself where are both trains at 5:00 P.M?

The New York train is 70 miles from Boston.

Now the New York is going to travel another x miles before they meet and it will take that train (since v=x/t), t = x/65 hours to get there.

The Boston train is going to travel (70 - x) miles when they meet. It will take that train t=(70-x)/70 hours to get there.

So two equations two unknowns.
t = x/65
t = (70-x)/70

solve for t, it will be in hours, multply by 60 to get minutes. (it will be greater than 30 minutes)

Time will be the minutes found above + 5:00 p.m, so something after 5:30

2006-10-09 15:46:58 · answer #1 · answered by ic3d2 4 · 0 0

The first train will be 130 miles closer to the second train when the second train leaves at 5:00 PM. They will be 70 miles apart at 5:00 pm.They are traveling at a combined speed of 135 miles per hour,or 2.25 miles per minute it will take 31.1 minutes ( 70 divided by 2.25 ) for the trains to pass each other.They will pass each other at 5:31 and 6 seconds PM

2006-10-09 22:50:02 · answer #2 · answered by Anonymous · 0 0

Here is how I would do it.

Let t be the amount of time in hours, after 5pm, that the trains meet.
At 5pm, the NY train will have already travelled 65*2=130 miles.
At this point, the trains are 70 miles apart.
After t hours, the NY train will have travelled 65t more miles.
After t hours, the Boston train will have travelled 70t miles.
65t + 70t = 70 miles
135t = 70
t = 0.5185 hours after 5pm, which is about 5:31pm.

Not sure if I did that right, so let me check my work.

NY train: (2.5185 hr) * (65 mph) = 163.7 miles
Bo. train: (0.5185 hr) * (70 mph) = 36.3 miles
163.7 mi + 36.3 mi = 200 miles.
Looks good to me.

2006-10-09 22:46:12 · answer #3 · answered by PJ 3 · 0 0

4:20

2006-10-09 22:37:43 · answer #4 · answered by Jared S 2 · 0 0

ye use the system of linear equations in two vars

2006-10-09 22:43:34 · answer #5 · answered by Lordimpalerthe 2 · 0 0

They wont meet...they will pass each other.
:)

2006-10-09 22:39:26 · answer #6 · answered by drdonlongjuan 1 · 0 0

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