The market price of hamburgers in a college town decreased recently, and the students in an economics class are debating the cause of the price decrease. Some students suggest that the price decreased because a new type of grill allows restaurants to cook a hamburger in half the time. Other students attribute the decrease in the price of hamburgers to a recent decrease in the price of pizza at local pizza parlors. Everyone agrees that the decrease in the price of pizza was caused by a recent decrease in the price of marinara sauce, which is not generally used in making hamburgers. Assume that burger joints and pizza parlors are entirely separate entities—that is, there aren't places that serve both hamburgers and pizza. The first group of students thinks the decrease in the price of hamburgers is due to the fact that a new type of grill allows restaurants to cook a hamburger in half the time.