Question

The fuel economy of a car, measured in miles per gallon, is modeled by the function f(s) = -0.009s² + 0.699s + 12 where s represents the speed of the car, measured in miles per hour. What's the fuel economy of the car when it travels at an average of 20 miles an hour?

a. -10.02 miles per gallon
b. 20 miles per gallon
c. 26.63 miles per gallon
d. 22.38 miles per gallon

Answer 1

The fuel economy of the car when it travels at an average of 20 miles per hour is 22.38 miles per gallon.

Step-by-step explanation:

To find the fuel economy of the car when it travels at an average speed of 20 miles per hour, we can substitute s = 20 into the given fuel economy function f(s) = -0.009s² + 0.699s + 12.

f(20) = -0.009(20)² + 0.699(20) + 12

f(20) = -0.009(400) + 0.699(20) + 12

f(20) = -3.6 + 13.98 + 12

f(20) = 22.38

Therefore, the fuel economy of the car when it travels at an average of 20 miles per hour is 22.38 miles per gallon.