Question 921486: Jerilyn has a $10 coupon and a 15% discount coupon for her favorite store. The store has a policy that only one coupon may be used per purchase. When is it best for Jerilyn to use the $10 coupon, and when is it best for her to use the 15% discount coupon.
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website!  price of the item, in $
$ = what Jerilyn would save on that item using the $10 coupon.
$ = what Jerilyn would save on that item using the 15% discount coupon.
THE MATH CLASS ANSWER:
If  <---> <---> , Jerilyn would save the same amount using either coupon.
For more expensive items, the 15% discount coupon saves more money:
 <---> <---> .
For less expensive items, the $10 coupon saves more money:
 <---> <--->
THE REAL WORLD ANSWER:
Actually, a 15% discount should be rounded to the nearest cent,
so 10.005 would be rounded to 10.01,
and 9.994 would be rounded to 9.99,
but anything in between would be rounded to 10.00.
That means that 15% off  would be rounded to  and the 15% discount would be better,
but 15% off  would be rounded to  and both coupons would save the same amount.
A 15% off  would be rounded to ,
but 15% off  would be rounded to  , and that would make the $10 off coupon a better bargain.
In conclusion,
Jerilyn should use the $10 coupon for prices up to $66.63,
and the 15% discount coupon for prices from $66.70 up.
For prices in between ($66.64 to $66.69) she could use either coupon.
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