The fuel economy of a car, measured in the miles per gallon, is modeled by the function f(s)= -0.0009s^2+ 0.699s+12 where s represents the average speed of the car, measured in miles per hour. what average speed results in the maximum fuel economy? a. -38.83 miles per hour b. 38.83 miles per hour c. 3.88 miles per hour d. 25.57 miles per hour

(b) suppose that consolidated power decides to use a level of significance of α = .05, and suppose a random sample of 100 temperature readings is obtained. if the sample mean of the 100 temperature readings is x⎯⎯ = 60.990, test h0 versus ha and determine whether the power plant should be shut down and the cooling system repaired. perform the hypothesis test by using a critical value and a p-value. assume σ = 5. (round your z to 2 decimal places and p-value to 4 decimal places.)