At any given price, the demand function reveals the quantity a consumer would pur- chase. The demand function also reveals the price a consumer would pay for any specific quantity. For example, in Figure at a price of USD 3 per trip, the consumer is observed to make 5 trips a year. This implies that he would pay USD 3 to make the fifth trip. If the price doubled to USD 6 per trip, the demand function in this example suggests the consumer would take only 3 trips. Thus, the consumer would pay USD 6 for the third trip. For each trip, the demand function reveals what the con- sumer would pay to take that specific tri