Question 2: The aim of this question is to review some of the basic concepts you have learned in the prerequisite courses. Consider the model yizmi+ei i=1,...,n Where 51,. . . ,6\" are independent and identically distributed as normal with mean 0 and variance 02. a. Using the least squares method, obtain the estimator of . b. What is the variance of the least squares estimator of ,8. (3. Obtain an estimator for 02. d. For the answers in parts (a) to (C), do we need the normality assumption? Why? e. For graduate students only. Redo parts (a) to (d), using the likelihood method