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Aragorn
 
 

GMATTERS - Counterintutive

by Aragorn Wed Apr 30, 2008 12:17 pm

In the PS section of the article. There is a formula for %change. A close look of the numbers reveals some inconsistencies in the use old old number versus new number. The article is here http://www.manhattangmat.com/strategy-s ... uition.cfm
Could you please tell us the correct formula. I think it is ..
(old value -new value)/old value.[/url]
UPA
 
 

Re: GMATTERS - Counterintutive

by UPA Thu May 01, 2008 10:57 pm

Aragorn Wrote:In the PS section of the article. There is a formula for %change. A close look of the numbers reveals some inconsistencies in the use old old number versus new number. The article is here http://www.manhattangmat.com/strategy-s ... uition.cfm
Could you please tell us the correct formula. I think it is ..
(old value -new value)/old value.[/url]


the formula is correct but there seems typos while putting the values in the link:

the formula for the % change = [new value - old value] / old value
StaceyKoprince
ManhattanGMAT Staff
 
Posts: 9360
Joined: Wed Oct 19, 2005 9:05 am
Location: Montreal
 

by StaceyKoprince Fri May 02, 2008 1:29 am

Hmm - something's not right there. I'll alert our curriculum director.

The way we really want to use the formula is:
larger number minus smaller number
over original number

Otherwise, you can end up with a negative number - what we really care about on the numerator is the difference between the two numbers.

So the easiest formula to remember is:
change / original

Then you don't have to keep straight what you subtract from what - just what's the difference? And put that over the original.
Stacey Koprince
Instructor
Director, Content & Curriculum
ManhattanPrep
Aragorn
 
 

Thanks

by Aragorn Sat May 17, 2008 3:40 pm

Thanks for the reply Stacey. I checked a practice problem from the student center, and it has the right formula you have indicated.
StaceyKoprince
ManhattanGMAT Staff
 
Posts: 9360
Joined: Wed Oct 19, 2005 9:05 am
Location: Montreal
 

by StaceyKoprince Mon May 26, 2008 11:19 am

You're welcome!
Stacey Koprince
Instructor
Director, Content & Curriculum
ManhattanPrep