Quandaries and Queries

Good day to you.

My name is Virginia.

I am confused and hope you can help. I have looked high and low for a "chart" persay to go by when I am having to calculate markup percentages.

Example if I have a List price of $1838.00 and my cost is $955.76 and I want to mark it up 30%. My colleage says it should be divided by .7

I don't understand how he arrives at .7 from 30 percent.

And sometimes the mark up is 20% or 25% -- how do I calculate that?????


Hi Virginia,

Some would say that percentages are the language of confusion. The fact that you are confused only prove that you are sane.

To mark up a price by 30%, I would myltiply it by 1.3 (that is, 100% + 30%). So with a price of $1838.00, a 30% percent mark up would be

$1838 * 1.3 = $2389.40. The price difference is $2389.40 - $1838.00 = $551.40, and 551.40/1838.00 = 0.30, that is, the price increase is 30% of the OLD price.

With your colleague's suggestion, you get

 $1838.00/0.7 = $2625.71. The price difference is now $2625.71 - $1838.00 = 787.71, and 787.71/2625.71 = 0.30, that is, the price increase is 30% of the NEW price.

In the news and commercials, we see lots of percentages used as above, without ever giving a precise meaning or a hint that there could be many interpretations possible. This is a classic example of "making numbers mean wathever you want them to mean". Part of the role of education in mathematics and other subjects is to help people feel less helpless in front of such an ever increasing flow of disinformation.


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