Problem 5 Assume that the normal random variables X1,X2, ..., X.\" of mean ,u and variance 0'2 are uncorrelated, i.e., oov(X.;,X j) = 0, for all 1 S 1' 7E j S n. (This happens, e.g., if X1,X2,...,Xn are independent.) If Sn = i 231 Xi is the average of the variables X 2', 2' = 1 : n, show that: E[Sn] = p, and was\") = i. 71, Problem 6 This is a Matlab exercise. 1. Save the Excel le \"hw3.xlsx\" from Blackboard or DEN in your MATLAB directory 2. Load the Excel le. Store the rst column as a vector x and the second column as a vector y. 3. Using the Curve Fitting Tool, nd a polynomial t for y = f (2:) Check polynomial ts with degree 1 to 9 and nd the one with the smallest RMSE. For step 2, use either the import tool or code. If you use the import tool, include a screenshot of it in your solutions. If you use code, include the commands you had to use. For step 3, include a screen-shot of the Curve Fitting tool, as well as the polynomial t you found. Note: The data represent the opening values for NASDAQ during the past year