A sales manager at a music store is looking at CD sales for the past year. She notices the following trend:

Selling Price (s)
Quantity Sold (q)
6
1,500
7
1,750
8
1,000
9
250

For every CD the store sells, $2 goes to maintaining the store, so it is not included in the profit.

The sales manager wants to use this data to find out the selling price that maximizes the store’s profit. Which should the 4th step be?

1. Plot s and q on a coordinate grid
2. Put s and q into slope-intercept form: $\displaystyle{q}=-{750}{s}+{7000}\usepackage{cmbright}\Huge\$
3. Create the Profit Formula $\displaystyle{P}={s}{q}-{2}{q}\usepackage{cmbright}\Huge\$
4.
5. Find the x-coordinate of the vertex by applying the formula $\displaystyle{x}=-\frac{{b}}{{{2}{a}}}\usepackage{cmbright}\Huge\$

Selling Price (s)	Quantity Sold (q)
6	1,500
7	1,750
8	1,000
9	250