The Carpet Cleaner Co. is attempting to do a better job of inventory management by predicting the number of vacuums the company will sell per week on the basis of the number of customers who respond to magazine advertisements in an earlier week. On the basis of a sample of n = 102 weeks, the following data were obtained:

a = 25 ( )2 Σ – c Y Y = 22,500 b = 0.10 ( )2 Σ – c Y Y = 45,000

(a) Provide a point estimate of the number of vacuums sold per week when 80 inquiries were received in the earlier week.

(b) Estimate (at the 95.5 per cent level) the number of vacuums sold per week when 80 inquiries were received the week earlier.

(c) State the value of the coefficient of determination.

(d) Explain the meaning of your r2 value.
[Ans.

(a) 33,

(b) Using the large-sample approximation, the interval is 3 to 63 because Sy–x=15

(c) 0.5

(d) 50 per cent of the variation in number of vacuums sold is explained by the magazine advertisements.]