University expenditure. An economist is interested in analyzing the yearly expenditure (in $ thousands) of a given university on facilities based on the total number of students enrolled at that university. The data file holds this information for 40 universities in town.

a) Find a regression model predicting the yearly expenditure from the total number of students for the sample of 40 universities.

b) Examine the residuals to determine if a linear regression is appropriate.

c) Test an appropriate hypothesis to determine if the association is significant.

d) What percentage of the variability in the yearly expenditure is accounted for by the regression model?