All work must be shown. Failure to do so will result in a grade of 0. The Department of Human Resources at York University has decided to invest their employees' pension fund in four different stocks (TD Bank, Tesla, Microsoft, Barrick Gold). They monitor yearly returns of these stocks and found the following results. Average Variance Sample size Sum(Ex) TD Bank =0.2233 = 0.0470 n1-9 1 = 2.01 Tesla 2=0.2600 = 0.0449 n2=11 2 = 2.86 Microsoft 3 = 0.2423 = 0.0221 n3.13 . = 3.15 Barrick Gold x4 = 0.3850 S = 0.1766 n4-10 . = 3.85 a) Can the Department of Human Resources conclude that there is a difference in mean yearly return between the three stocks (TD Bank, Tesla, Microsoft)? Use a 1% significance level. b) Can they infer at 5% significance level that the TD Bank stock is riskier than Tesla stock? c) Estimate the variability of the yearly returns of Barrick Gold stock with 90% confidence.