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QUESTION 26 Find the confidence level related to the critical value za/2=1.723. O 88.4% O 89.2% O 96.5% 0 91.5% QUESTION 27 A journal article reports that a random sample of 22 antivirus software packages was used as a basis for calculating a 97% t-based confidence interval for the true mean annual cost of an antivirus software in UAE. The resulting interval was (217 Dhs, 291 Dhs). What is the sample mean cost used when computing the interval? Round your answer to two decimal places. QUESTION 28 Find the confidence level related to the critical value to/2= -2.95 where the sample size n =8. O 97.9% 96.5% 99.9% 0 93.9% QUESTION 29 A car insurance company wanted information about the age of its customers. A researcher computed 90%, 95%, 97%, and 99% confidence intervals for the population mean age of the customers. Which of the following intervals is the the 99% confidence interval for the population mean age? (36.70, 39.30) (36.56, 39.44) (36.30, 39.70) (36.91, 39.09) QUESTION 30 The rates of return on 7 natural resources mutual funds are given below: 16.83 17.77 14.87 18.88 16.55 14.44 15.89 Suppose that the rates are approximately normal. (a) Compute the mean and the standard deviation rate of return of natural resources mutual funds. Round your answer to three decimal places. (b) Calculate the lower confidence limite and the upper confidence limite of the 99% confidence interval for u, the mean rate of return of natural resources mutual funds. Round your answer to three decimal places