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# What is the difference between percentage change, and...

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What is the difference between percentage change, and... [#permalink]

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27 Feb 2012, 22:02
I understand the formula for percentage change is:

end value - start value/ start value = x% or percentage change.

and percentage of is

x * x%/100 = z

i.e.

10 x 100/100 = 10%

however you can use percentage of to calculate percentage change, like this:

ex 1.

percentage change:

60-50/50 * 100 = 20%

Using percentage of:

50 x y% = 60

y = 60/50*100 = 120

I can't seem to understand why you would use one over the other, when you can get the same result using either.

Cheers
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Re: What is the difference between percentage change, and... [#permalink]

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28 Feb 2012, 19:33
On the GMAT it seemed to me very obvious when to use any of the percentage-based formulas - the question itself was the indicator. I do not recall ever really having to make any assumptions or guesses between the two options.

If you are asking in more general terms (i.e. what is the practical application of each?) - I prefer percentage change in sales reporting as it is generally easier for others to grasp. I have yet to come across a practical use for percentage of with the exception of seeing it used to make a change or difference seem larger (e.g. would you rather report a 5% increase in sales or sales being at 105% of last period? anyone paying attention would see through the tactic but some may miss it). I don't use percentage of pretty much as a rule.
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Re: What is the difference between percentage change, and... [#permalink]

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29 Feb 2012, 04:33
theknighht wrote:
I understand the formula for percentage change is:

end value - start value/ start value = x% or percentage change.

and percentage of is

x * x%/100 = z

i.e.

10 x 100/100 = 10%

however you can use percentage of to calculate percentage change, like this:

ex 1.

percentage change:

60-50/50 * 100 = 20%

Using percentage of:

50 x y% = 60

y = 60/50*100 = 120

I can't seem to understand why you would use one over the other, when you can get the same result using either.

Cheers

When a value increases/decreases and you know both the original and the final values, you find the percentage change.
Say your score was 500 and now it is 600. The percentage change is (600 - 500)/500 * 100 = 20%

'percentage of' is used in many situations e.g. You might have the initial value and percentage increase/decrease. You need to find the final value.
Your GMAT score has increased by 20%. Your first GMAT score was 500. What is the 20% of 500?
(20/100) * 500 = 100
So your new GMAT score must be 500 + 100 = 600 (final value)

Another example for 'percentage of'
There are total 120 students in a class. Out of these, 48 are boys. What 'percentage of' students are boys?
We need to find this - 48 is what percentage of 120? Say 48 is x% of 120.
120 * x/100 = 48
x = 40%
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Re: What is the difference between percentage change, and...   [#permalink] 29 Feb 2012, 04:33
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# What is the difference between percentage change, and...

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