Commercial airlines need to know the operating cost per hour of flight for each plane in their fleet. In a study of the relationship between operating cost per hour and number of passenger seats, investigators computed the regression of operating cost per hour on the number of passenger seats. The 12 sample aircrafts used in the study included planes with as few as 216 passenger seats and planes with as many as 410 passenger seats. Operating cost per hour ranged between $3600 and $7800.

Commercial airlines need to know the operating cost per hour of ight for each plane in their eet. In a study - of the relationship between operating cost per hour and number of passenger seats, investigators computed the regression of operating cost per hour on the number of passenger seats. The 12 sample aircraft used in the study included planes with as few as 216 passenger seats and planes with as many as 410 passenger seats. Operating cost per hour ranged between $3,600 and $7,800. Some computer output from a regression analysis of these data is shown below. 7 - ' SCATTERPLOT WITH ' LEAST SQUARES REGRESSION LINE ' 8000 's' E 7000 a: E... . g 6000 on g 5000 s 4000 200 300 400 Number of Passenger Seats Predictor ' Coef StDev T P Constant ' 1 136 1226 0.93 0.376 Seats 14.673 4.027 3.64 0.005 s = 845.3 RSq = 57.0% ' RSq-(adj) = 52.7% (a) What is the equation of the least squares regression line that describes the relationship between operating cost per hour and number of passenger seats in the plane? Define any variables used in this equation. (b) What is the value of the correlation coefcient for operating cost per hour and number of- passenger seats in the'plane? Interpret this correlation. (c) Suppose that you want to describe the relationship between operating cost per hour and number of passenger seats in the plane for planes only in the range of 250 to 350 seats. Does the line shown in the scatterplot still provide the best description of the relationship for data in this range? Why or why not