The Intercity Bus Company is concerned with the high cost of fuel. The company believes that fuel is being wasted because drivers are exceeding the speed limit. A series of tests (N = 85) shows the following relationship between bus speed (X) and miles per gallon of fuel (Y) for speeds between 35 and 85 miles per hour (mph):
= 12.4 - .11X sb = .007 Sy|x = .41 r2 = .98
= 50 sx = 15
Intercity is considering placing a governor on all buses, limiting their speed to 55 mph. At an average speed of 55 mph, how many miles per gallon would a bus get? Place a 95% confidence limit around this estimate.