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#1 2010-03-20 17:21:51

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

Speed

If a vehicle increases its speed by 2km/h to its initial speed, it will take half an hour less to travel a
distance of 240km. Find its speed.


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#2 2010-03-20 18:08:53

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Speed

Hi soha;

It's velocity is:

Woops, sorry soha. Didn't read the problem correctly. thought it was 1 hour difference instead of 1 / 2 . Ignore this answer.

Last edited by bobbym (2010-03-21 09:50:42)


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 2010-03-21 02:46:11

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

Re: Speed

481?????

I did'nt understand


"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!" smile smile
- David O. McKay

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#4 2010-03-21 03:34:37

soroban
Member
Registered: 2007-03-09
Posts: 452

Re: Speed


. .






. .

.

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#5 2010-03-21 03:48:27

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

Re: Speed

I did'nt understand why you multiplied by 2s(s+2),, and the following steps;

Please explain why you did it ??


"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!" smile smile
- David O. McKay

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#6 2010-03-21 11:02:25

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Speed

Hi soha;

Soroban has answered the question correctly. Here is my correction from post #2 where I used 1 hour instead of 1/2 hour. Looks like I need more practice than you do, so I did it again.

Using d = v * t you get:


Expand the RHS:

Solve for t in the first equation:

Substitute for t

Solve for v:

v = 30, v = - 32

We reject v = -32, so v = 30 km / h


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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#7 2010-03-21 18:57:46

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

Re: Speed

if we use the equation time=distance/speed , and the speed as x
we get,
first time=240/x

after increaing the speed, time= 240/x+2

240/x - 240/x + 2 = 1/2


I got the answer by this way
Can we solve it by this way ?? Is this method correct??

Last edited by soha (2010-03-21 19:00:23)


"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!" smile smile
- David O. McKay

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#8 2010-03-21 20:56:10

ZHero
Real Member
Registered: 2008-06-08
Posts: 1,889

Re: Speed

yeah ... u can!!!


If two or more thoughts intersect, there has to be a point!

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#9 2010-03-21 21:00:59

soha
Real Member
Registered: 2006-07-07
Posts: 2,530

Re: Speed

thats good then


"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!" smile smile
- David O. McKay

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