suggesting that revenue will be zero for a charge of 0 or for a charge of 12, and that fixed expenses are 4700. Charges less than 0 are uninteresting, and charges high enough to cause the number of customers to be negative also don't make any sense in this context.
Though out of the range of likely consideration, charges low or high enough to cause profit to be negative (more than 9.54, for example) seemingly can be reasonably modeled by this function.
