68. Environment: Fuel Economy. Gas mileage (miles per gallon, mpg) can be approximated by a quadratic function of speed. For a particular automobile, assume the vertex occurs when the speed is 50 miles per hour (the mpg will be 30). a. Write a quadratic function that models this relationship, assuming 70 miles per hour corresponds to 25 mpg. b. What gas mileage would you expect for this car driving 90 miles per hour? 45 35 (50, 30) (70, 25) 25 15 10 30 90 Speed (mph) MPG 50 70 245

The owner of a local hair salon is planning to raise the price for a haircut and blow dry. The current rate is $30 for this service, with the salon averaging 550 clients a month. A survey indicates that the salon will lose 5 clients for every incremenetal price increase of $2.50. a. Write an equation to model the salon’s monthly revenue, R, in dollars, as a function of x, where x represents the number of $2.50 increases in price. b. Use the product rule to determine R’(x). c. Solve for R’(x) = 0.

Please help to solve d

7. Sky Launch Trampoline Park charges Customers $9.50 per hour they spend jumping. Each customer must also pay $2.50 for grip socks. Write an equation in slope-intercept form to represent this linear function. Derrick spent $31 at Sky Launch Trampoline Park on Sunday. How many hours did he jump?