SOLUTION: A sorority buys a case of sweatshirts for $480 to sell at a mixer. The sorority needs to sell all but 16 of the sweatshirts at a profit of $5 per sweatshirt to regain the $480 inve

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Question 1160413: A sorority buys a case of sweatshirts for $480 to sell at a mixer. The sorority needs to sell all but 16 of the sweatshirts at a profit of $5 per sweatshirt to regain the $480 investment. How many sweatshirts must be sold, and at what price, to do this?
_sweatshirts at $ _per sweatshirt

Answer by ikleyn(52835) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let "n" be the number of sweatshirts .


From the condition, you have this equation to find n

    480%2F%28n-16%29 - 480%2Fn = 5  dollars.    (1)


Cancel the factor 5 in both sides

    96%2F%28n-16%29 - 96%2Fn = 1.


To solve the equation, multiply both sides by n*(n-16). You will get then

    96n - 96*(n-16) = n*(n-16)


Simplify and reduce to the standard form quadratic equation

    96n - 96n + 96*16 = n^2 - 16n

    n^2 - 16n - 1536 = 0

    n = %2816+%2B-+sqrt%2816%5E2+%2B+4%2A1536%29%29%2F2 = %2816+%2B-+sqrt%286400%29%29%2F2 = %2816+%2B-+80%29%2F2.


The only positive root is  n =  %2816+%2B+80%29%2F2 = 96%2F2 = 48.


ANSWER.  n = 48 shirts.


CHECK.  I will check equation (1):  480%2F%2848-16%29 - 480%2F48 = 480%2F32 - 480%2F48 = 15 - 10 = 5.

        ! Correct !

Solved.