An establishment specializing in mail order deliveries fits a regression to predict the number of mail orders over a period of 38 months. The Durbin-Watson statistic on residuals is 0.875.

a) At a = 0.01, using k = 1 and n = 50, what are the values of dL and dU?

b) Is there evidence of positive autocorrelation? Explain.

c) Is there evidence of negative autocorrelation? Explain.