06-07-2006, 10:45 AM
You can't take a percentage calculation of a percentage.
Example:
Tshirt $10.00 It's on Sale so you get a 5% discount, but today is the 10th anniversary of the store so every purchase gets an additional 10% discount on the final price.
You would assume that would mean a 15% overall discount...but watch
$10.00 X 5% discount = $9.50 now apply the additional 10% discount:
$9.5 X 10% discount = $8.55 final price
Whereas, were you to give a 15% discount off of $10.00 the price would be:
$10.00 X 15% discount = $8.50
The 2 numbers are close but they aren't the same.
So, to answer your question you have to go with your first calculation of 7.98% (depending on how many significant digits you want) rather than trying to get an average of percentages
Example:
Tshirt $10.00 It's on Sale so you get a 5% discount, but today is the 10th anniversary of the store so every purchase gets an additional 10% discount on the final price.
You would assume that would mean a 15% overall discount...but watch
$10.00 X 5% discount = $9.50 now apply the additional 10% discount:
$9.5 X 10% discount = $8.55 final price
Whereas, were you to give a 15% discount off of $10.00 the price would be:
$10.00 X 15% discount = $8.50
The 2 numbers are close but they aren't the same.
So, to answer your question you have to go with your first calculation of 7.98% (depending on how many significant digits you want) rather than trying to get an average of percentages