l l-:- w ' Afrom 'C (- C imathas.humber.ca _ Apps I1} HUI'leERL'DLLEGE STATUTE (c) Compare parts (a) and (b). Select the correct statement. 59m 0 If the confidence level decreases, then the required sample size does not change. 0 If the confidence level decreases, then the required sample size also decreases. 0 If the condence level decreases, then the required sample size increases. (d) Suppose that the confidence level remains invariant. How should we change the sample size to achieve the larger confidence interval? 0 Decrease the sample size. 0 Increase the sample size. 0 Do nothing as the length of the confidence interval does not depend on the sample size. Question Help: E Message instructor Add Work l l-o *- ' Afro-n1 'C (- C imathas.humberica _ Apps I1} HUMEEREDLLEGE STATUTE The employees ofa large international company would like to have vision care as part of their benefits package. A researcher needs to estimate the amount of money that employees and their beneficiaries spend on such treatment, on average. A sample of 1156 employees reveals the mean amount spent last year was $805.95, with a standard deviation of$114.01. We assume that the population standard deviation is close to the last number. (a) Construct a 90% confidence interval for the population mean amount spent on vision care. Round the condence interval values to 2 decimal places. What is the 90% confidence interval? (b) Construct a 99% confidence interval for the population mean amount spent on vision care. 2