13.11 Consider the accompanying data on x 5 advertising share and y 5 market share for a particular brand of soft drink during 10 randomly selected years.

x .103 .072 .071 .077 .086 .047 .060 .050 .070 .052 y .135 .125 .120 .086 .079 .076 .065 .059 .051 .039

a. Construct a scatterplot for these data. Do you think the simple linear regression model would be appropriate for describing the relationship between x and y?

b. Calculate the equation of the estimated regression line and use it to obtain the predicted market share when the advertising share is .09.

c. Compute r2. How would you interpret this value?

d. Calculate a point estimate of s. On how many degrees of freedom is your estimate based?