Solve the problem.
-When going more than 38 miles per hour, the gas mileage of a certain car fits the model y = 43.81 - 0.395x where x is the speed of the car in miles per hour and y is the miles per gallon of gasoline. Based on this model, at what
Speed will the car average 15 miles per gallon? (Round to nearest whole number.)
A) 98 mph
B) 48 mph
C) 149 mph
D) 73 mph

Question

Quizplus · Accepted Answer

To find the speed at which the car averages 15 miles per gallon, we set y = 15 in the equation and solve for x: 15 = 43.81 - 0.395x. Rearranging the equation gives 0.395x = 43.81 - 15, which simplifies to 0.395x = 28.81. Dividing both sides by 0.395 gives x ≈ 72.94, which rounds to the nearest whole number as 73 mph.

Solve the Problem. -When Going More Than 38 Miles Per Hour, the Gas