2. (A record) A record of annual percentage rates of return of the stock S is shown in Table 9.5. Month 13 Percent rate of return 4.2 4.5 14 15 16 TABLE 9.5 RECORD OF RATES OF RETURN Month Percent rate of return 1 1.0 2. .5 3 4.2 4 -2.7 5 -2.0 6 7 -3.1 8 4.1 9 1.7 .1 11 -2.4 12 3.2 17 -2.5 2.1 -1.7 3.7 3.5 18 19 3.2 10 20 21 22 23 24 -2.4 2.7 2.9 -1.9 1.1 (a) Estimate the arithmetic mean rate of return, expressed in percent per year. (b) Estimate the arithmetic standard deviation of these returns, again as percent per year. (c) Estimate the accuracy of the estimates found in parts (a) and (b). (d) How do you think the answers to (c) would change if you had 2 years of weekly data instead of monthly data? (See Exercise 1.)