12.95 Based on the 28 online purchase data, an attempt was made to explain number purchases made from an online store per hour. The model fitted was as follows:

y = b0 + b1x1 + b2x2 + e where y = number of purchases per hour x1 = processing speed x2 = product quality The least squares parameter estimates (with standard errors in parentheses) were (Ghatak and Deadman 1989) as follows:

b1 = 1.379810.21902 b2 = 0.750410.08262 The adjusted coefficient of determination was as follows:

R2 = 0.7387

a. Find and interpret a 99% confidence interval for b1.

b. Test, against the alternative that it is positive, the null hypothesis that b2 is 0.

c. Find the coefficient of determination.

d. Test the null hypothesis that b1 = b2 = 0.

e. Find and interpret the coefficient of multiple correlation.