Question: A fast food chain decided to carry out an experiment to asses the influence of advertising expenditure on sales. Different relative changes in advertising expenditure, compared to the previous year, were made in eight regions in the country, and resulting changes in sales levels were observed. The accompanying table shows the results

a) Estimate by least squares the linear regression of increase in sales on increase in advertising expenditure.

b) Interpret the estimate for the slope.

c) Find a 90% confidence interval for the slope of the population regression model.

d) Test the hypothesis, at 5% significance level, that the slope coefficient is less than or equal to zero against the hypothesis that it is greater than zero. Interpret the result.

e) Interpret the value obtained for R2.(r square)