Final answer:
The average rate of change in gallons of gas per year from 1960 to 1999 is -2.97 gal/year. This means that the average fuel consumption per year of a passenger car in the U.S. decreased by nearly 3 gallons per year.
Step-by-step explanation:
To determine the average rate of change of fuel consumption per year from 1960 to 1999, follow these steps:
Gather the data: Suppose you have the average fuel consumption per year for passenger cars in the U.S. for the years 1960 and 1999. Let's assume the fuel consumption in 1960 was 668 gallons per year and in 1999 was 552 gallons per year.
Calculate the change in fuel consumption: Subtract the fuel consumption in 1960 from the fuel consumption in 1999 to find the total change in fuel consumption over the 39-year period:
Change in fuel consumption = 552 gallons/year - 668 gallons/year = -116 gallons/year
Calculate the average rate of change: Divide the change in fuel consumption by the number of years to find the average rate of change per year:
Average rate of change = -116 gallons/year / 39 years/year = -2.97 gallons/year
Interpret the result: Since the average rate of change is negative (-2.97 gallons/year), it means that the average fuel consumption per year of a passenger car in the U.S. decreased by 2.97 gallons per year between 1960 and 1999.
Therefore, the correct answer is d. -2.97 gal/year; the average fuel consumption per year of a passenger car in the U.S. decreased by nearly 3 gal/year.