7-49 An investment bank is interested in monitoring the weekly amount (in millions of dollars) invested in volatile stocks so as to maintain a stable rate of return on a selected fund. Table 7-31 shows 25 consecutive weeks of the amount invested ($M) in the fund. Construct appropriate control charts and comment on the stability of invest- ment. Revise the chart, if necessary, assuming special causes for out-of-control points. What is your estimate of the standard deviation of the weekly amount invested? 386 CONTROL CHARTS FOR VARIABLES TABLE 7-31 Weekly Investment in Volatile Stocks Week Investment (SM) Week Investment (SM) Week Investment (SM) 16.2 10 12.9 19 16.3 10.8 11 28.5 20 14.2 18.9 12 23.3 21 21.5 U t WN 14.4 13 20.2 22 18.6 15.7 14 19.3 23 20.9 25.3 15 14.8 24 22.4 20.4 16 18.7 25 21.8 10 00 22.6 17 20.4 17.8 18 21.2 7-50 Refer to Exercise 7-49 and the revised process. Is this process capable of meeting a goal value of $1.5M for the standard deviation of the weekly amount invested? Construct an appropriate chart and discuss