20. For a random sample of U S. counties, data are obtained on X = percentage of the popo- lation aged over 50 and Y = per student expenditure on education. Table 9.15 is part of the computer printout for the analysis.

a) What was the sample size for this study?

b) Fill in the blanks in Table 9.15. TABLE 9.15 Sum of Source DE Squares Mean Square Root MSE R-square Model 1 Error 400000 Total 49 500000 Parameter Standard Variable Estimate Error INTERCEP 1300.0 6.334 T for H0: Parameter=0 205.2 Prob T .0000 AGE -5.0 1.443