Train B Overtakes Train ADate: 01/17/2002 at 10:46:15 From: Vickie Subject: Train problem Train A leaves the station traveling at 30 miles per hour. Two hours later train B leaves the same station travelling in the same direction at 40 miles per hour. How long does it take for train B to catch up to train A? Could you just walk me through this? Date: 01/17/2002 at 11:46:20 From: Doctor Jeremiah Subject: Re: Train problem Hi Vickie, If train A is going 30 miles/hour, then the amount of distance it can go in a certain time (call it t) is: 30 miles/hour * t hours = 30t miles The second train starts out 2 hours later, so for it the time it is travelling is t-2. That menas that train B (going 40 miles per hour) can go this distance in t-2 hours: 40 miles/hour * (t-2) hours = 40(t-2) miles The question says that train B catches up with train A (which mean that they go the same distance), so that means: 30t = 40(t-2) Solve for t to find the number of hours the trains were travelling. - Doctor Jeremiah, The Math Forum http://mathforum.org/dr.math/ |
Search the Dr. Math Library: |
[Privacy Policy] [Terms of Use]
Ask Dr. Math^{TM}
© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/dr.math/