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#1 2014-07-20 20:06:12
problem on trains
Need help to solve math homework problem
A train overtakes two persons walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. Then what is the length of the train?
Thanks
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#2 2014-07-21 01:57:44
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: problem on trains
Hi;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#3 2014-07-25 21:48:12
- Nehushtan
- Member
- Registered: 2013-03-09
- Posts: 957
Re: problem on trains
Let the length of the train (in km) be .
Let the speed (in kph) of the train relative to the first person be ; then its speed relative to the second person is .
Let the speed (in kph) of the train relative to the first person be ; then its speed relative to the second person is .
Therefore:
Hence:
So the train’s length is 0.05 km – i.e. 50 m.
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#5 2014-09-15 23:51:58
- GreatSandy
- Member
- Registered: 2014-09-15
- Posts: 15
Re: problem on trains
the train’s length is 5000 cm
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