The Joint Strike Fighter (JSF) program, operated by the U.S. Department of Defense, is a global defense program that involves acquisition of military fighter jets for participating allied countries. An article in the Air & Space Power Journal (March-April 2014) reported on the estimated annual cost of adding a military aircraft to the JSF program. The table below lists the year of initial operation and cost (in millions of dollars) for 12 JSF military aircraft models. For this problem, let y = estimated annual cost and x = year of initial operation for each aircraft model.

a. Fit the simple linear regression model, E(y) = β0 + β1x, to the data.

b. If possible, give a practical interpretation of the y-intercept of the line.

c. Give an estimate of the increase in the cost of adding a military aircraft to the JSF program each year.

Cost Year Model 1974 1975 1977 F-14 F-15AB A-10 FA-18AB 40 28 13 1978 1978 1979 1981 1987 1989 26 30 16 20 29 31 F-15CD F-16AB F-16CD FA-18CD F-15E 1998 2005 2012 FA-18EF F-22 55 105 80 F-35