SOLUTION: Hello can someone please help with this word problem. A certain bakery has found that the daily demand for blueberry muffins is 3200/p, where p is the price on a muffin in cents.

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Hello can someone please help with this word problem. A certain bakery has found that the daily demand for blueberry muffins is 3200/p, where p is the price on a muffin in cents.       Log On


   



Question 818234: Hello can someone please help with this word problem.
A certain bakery has found that the daily demand for blueberry muffins is 3200/p, where p is the price on a muffin in cents. The daily support is 3p-200. Find the price at which supply and demand are equal.
I get 35 and my answer key is saying .80 so I was hoping to get some help here
3200/p = 3p-200
then I multiplied by p
which gave me 3200=3p^2-200p
in standard form
3p^2-200p-3200=
this was my start and in the end I ended up with 35. Is my start wrong?
Thank you! :-)

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
Your start is right, you must have made some calculation error.
If supply is 3p-200 and demand is 3200%2Fp
3200%2Fp+=+3p-200 is the right equation to make supply equal demand.
Also, from 3200%2Fp+=+3p-200 you get 3200=3p%5E2-200p
and 3p%5E2-200p-3200=0 as you meant to write.

I see 3 ways to solve that equation:
factoring, completing the square, and using the quadratic formula.
Since I had my calculator next to me,
I found it easier to use the quadratic formula,
which says that the solutions to ax%5E2%2Bbx%2Bc=0 can be calculated as
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In your case, a=3 , b=-200 , and c=-3200 , so
x+=+%28200+%2B-+sqrt%28200%5E2-4%2A3%2A%28-3200%29%29%29%2F%282%2A3%29+
x+=+%28200+%2B-+sqrt%2840000-38400%29%29%29%2F6
x+=+%28200+%2B-+sqrt%2878400%29%29%29%2F6
x+=+%28200+%2B-+280%29%29%2F6
The solution with the minus sign, x=%28200-280%29%2F6=-80%2F6=-40%2F3
does not make sense, because the price has to be a positive number of cents.
The other solution is
x=%28200%2B280%29%2F6=480%2F6=80 ,
meaning that pricing each muffin at 80 cents will make supply meet demand.