A sales manager collected the following data on annual sales for new customer accounts and the number of years of experience for a sample of salespersons. Salesperson Years of Experience Annual Sales ($1000)
1 1 85
2 1 84
3 2 92
4 2 87
5 4 97
6 4 94
7 6 107
8 7 115
9 7 112
10 9 118

a. Compute the residuals and choose a residual plot for this problem. (to 1 decimal)
b. Develop a scatter diagram for these data with years of experience as the independent variable.
c. Develop an estimated regression equation that can be used to predict annual sales given the years of experience.
d. Use the estimated regression equation to predict annual sales for a salesperson with 9 years of experience.