12.96 Based on data on 2,679 high school basketball players, the following model was fitted:

y = b0 + b1x1 + b2x2 + g + b9x9 + e where y = minutes played in season x1 = field@goal percentage x2 = free@throw percentage x3 = rebounds per minute x4 = points per minute x5 = fouls per minute x6 = steals per minute x7 = blocked shots per minute x8 = turnovers per minute x9 = assists per minute The least squares parameter estimates (with standard errors in parentheses) were as follows:
b0 = 358.848 144.6952 b1 = 0.6742 10.06392 b2 = 0.2855 10.03882 b3 = 303.81 177.732 b4 = 504.95 143.262 b5 = -3923.5 1120.62 b6 = 480.04 1224.92 b7 = 1350.3 1212.32 b8 = -891.67 1180.872 b9 = 722.95 1110.982 The coefficient of determination was as follows:
R2 = 0.5239

a. Find and interpret a 90% confidence interval for b6.

b. Find and interpret a 99% confidence interval for b7.

c. Test, against the alternative that it is negative, the null hypothesis that b8 is 0. Interpret your result.

d. Test, against the alternative that it is positive, the null hypothesis that b9 is 0. Interpret your result.

e. Interpret the coefficient of determination.

f. Find and interpret the coefficient of multiple correlation.