Consider the simple linear regression model yi = 0 + 1xi + i, i = 1, 2, n (1) a) Find the least squares estimator 1 for model (1) when 0 = 0. Derive Var( 1) and also a 100(1 )% confidence interval for 1 .

b) Compare the variances of 1 when i) intercept is in the regression model (1) and ii) intercept is not in the regression model (1). c) What is the implication for the regression model (1) if 1 = 0 so that the model is yi = 0 + +i? What kind of plot would be on a graph? You don't need to plot it but you need to explain.