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Percentage of Increase


Date: 07/23/97 at 13:45:49
From: Lisa Zone 
Subject: Percent increases

I need to figure out the percent increase for an article I am writing. 
The figure in 1995 was 50,000 and the estimated figure for 2000 is 
325,000.  I need to figure out how much of a percent increase that is. 
I know 100,000 would be a 100 percent increase, right?  But then, how 
do I go to the 325,000?  I need the figure to add piece.  Can you 
help? 
 
Thanks.


Date: 07/24/97 at 15:40:54
From: Doctor Rob
Subject: Re: Percent increases

The increase is 325,000 - 50,000 = 275,000.  As a fraction of the 
original this is 275,000/50,000 = 11/2 = 5.50 . To convert a decimal 
to a percentage, multiply by 100.  This gives a percentage increase of 
550 percent.

See http://mathforum.org/dr.math/faq/faq.fractions.html    for 
more on fractions, decimals, and percentages.

-Doctor Rob,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   


Date: 08/03/97 at 13:41:26
From: Doctor Terrel
Subject: Re: Percent increases

Dear Lisa,

You have every right to feel a little confused on a problem like this.  
It has been my experience that problems involving percents greater 
than 100 are confusing to the majority of people.  But never fear; Dr. 
Math is here!

I would attack this problem in two stages: (1) find the "amount" of 
increase; then (2) find what percent that the increase is of the base 
figure.

(1) The amount is rather easy.  It's 275,000  [325,000  -  50,000].

(2) When I wish to find out what percent one thing is of another 
    (regardless if it is greater or less than 100 percent), I set 
    things up this way:

    base value  x  n%  =  percentage value

    In your problem this comes out as 

    50,000  x  n%  =  275,000

                       275,000
               n%  =  ---------  =  5.5  =  550%
                        50,000

You can choose two ways to express your answer now.  One is to say: 
there will be a 550% increase by the year 2000.  Or you can say: in 
the year 2000 the (new value) - you didn't say what the numbers 
represented, so I'm a little confused right here - will be about five 
and a half times greater than what it was in 1995.

Many people don't quite grasp those phrases, especially the latter 
one. Instead you might wish to say it this way: in 2000 the (new 
value) will be 6 and a half times what it was in 1995. The difference 
in the wording is subtle, of course, but important.  The number 6 1/2 
comes from

    325,000
   ---------  =  6.5  or  6 1/2
     50,000

which is NOT a percent increase situation. Either way is acceptable, 
however.  Use whichever you feel more comfortable with, and your 
writing will be more clear.

Good luck on your article. 

-Doctor Terrel,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Fractions

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