A sporting goods store uses quadratic equations to monitor the daily cost and profit for various items it sells. The store’s daily profit, y, when soccer balls are sold at x dollars each, is modeled by mc001-1. Jpg. Why is there an interval over which the graph decreases? If the store sells more soccer balls, they can decrease the price. If the soccer balls are returned for a refund, the store will lose money. If the soccer balls are too expensive, fewer will be sold, reducing profit.