The marketing department of a company estimates that the demand for a product is given by $p=100-0.0001 x$, where $p$ is the price per unit and $x$ is the number of units. The cost $C$ of producing $x$ units is given by $C=350,000+30 x$, and the profit $P$ for producing and selling $x$ units is given by
$P=R-C=x p-C$
Sketch the graph of the profit function and estimate the number of units that would produce a maximum profit. Verify your estimate using a graphing utility.