SOLUTION: I am having a problem fitting my factors into the quadratic equation. The question is as follows: A retailer spent $48 to purchase a number of special mugs. Two of them were b

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: I am having a problem fitting my factors into the quadratic equation. The question is as follows: A retailer spent $48 to purchase a number of special mugs. Two of them were b      Log On


   



Question 5014: I am having a problem fitting my factors into the quadratic equation. The question is as follows:
A retailer spent $48 to purchase a number of special mugs. Two of them were broken in the store, but by selling each of the remaning mugs for $3 above original cost per mug, she made a total profit of $22.00.
How many mugs were originally purchased?
**If anyone could just give my brain a push, I would be more than grateful!! It's been 15 years since I have used the quadratic equation and I am just stuck!!
Thank you in advance!!

Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
Define: Let x = number of mugs bought.
She broke 2, so she sold (x-2) mugs.
Each mug cost to buy 48/x, but she sold them at 3+(48/x) dollars for a total of 48+22 --> $70.

So, (saleprice per mug)x(number of mugs) = income
(3+(48/x))(x-2) = 70

Multiply both sides by x --> x%283%2B%2848%2Fx%29%29%28x-2%29+=+70x
%283x%2B%2848x%2Fx%29%29%28x-2%29+=+70x
%283x%2B48%29%28x-2%29+=+70x
--> 3x%5E2+-+6x+%2B+48x+-+96+=+70x. Collect all terms on left hand side:

3x%5E2+-+28x+-+96+=+0
This actually factorises to (3x+8)(x-12) = 0 which means that either 3x+8=0 Or x-12=0.

Now, x cannot be -8/3, since x is the number of mugs...-8/3 mugs???, so the answer is she originally bought 12 mugs.
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If you do want to use the quadratic formula:

x = %28-b+%2B-+sqrt%28b%5E2+-+4ac%29%29%2F%282a%29

where
a = 3
b = -28
c = -96

--> x = %28-%28-28%29+%2B-+sqrt%28%28-28%29%5E2+-+4%283%29%28-96%29%29%29%2F%282%283%29%29
--> x = %2828+%2B-+sqrt%28784+%2B+1152%29%29%2F6
--> x = %2828+%2B-+sqrt%281936%29%29%2F6
--> x = %2828+%2B-+44%29%2F6
so either x = %2828+%2B+44%29%2F6 or x = %2828+-+44%29%2F6

x=72/6 or x=-16/6

--> x=12

jon.