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6 A random sample of 25 items is drawn from a population whose standard deviation is unknown. The sample mean is = 850 and the sample standard deviation is s= 15. Use Appendix D to find the values of Student's t. points (a) Construct an interval estimate of / with 95% confidence. (Round your answers to 3 decimal places.) The 95% confidence interval is from e Book o Ask (b) Construct an interval estimate of / with 95% confidence, assuming that s = 30. (Round your answers to 3 decimal places.) The 95% confidence interval is from Print References (c) Construct an interval estimate of / with 95% confidence, assuming that s = 60. (Round your answers to 3 decimal places.) The 95% confidence interval is from to (d) Describe how the confidence interval changes as s increases. O The interval stays the same as s increases. O The interval gets wider as s increases. O The interval gets narrower as s increases.palms 930:\": Ask Print References A random sample of 15 pharmacy customers showed the waiting times below [in minutes}. 15 1Q 15 13 13 2E! 19- 13 22 9 19 22 13 29 24 19 Click here for the Excel Data File Find a 90 percent condence interval for p. assuming that the sample is from a normal population. [Round your standard deviation answer to 4 decimal places and t-value to 3 decimal places. Round your answers to 3 decimal places.) The 90% condence interval to: l:l 8 Calculate the standard error. May normality be assumed? (Round your answers to 4 decimal places.) Standard Error Normality 5 n = 25, (a) 7T points (Click to select) v = .55 n = 50, (b ) (Click to select) v = .28 n = 113, e Book (c) (Click to select) v = . 45 n = 491, (d) 71 (Click to select) v Ask = . 902 Print References9 Should p be assumed normal? (a) n = 50, 1 = .40 5 points O No O Yes eBook (b) n = 150, IT = .04 Ask O Yes O No Print References (c) n = 150, / = .02 O No O Yes10 Of 54 bank customers depositing a check, 23 received some cash back. (a) Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back. (Round your answers to 4 5 decimal places.) points The 90% confidence interval is from to eBook (b) May normality of p be assumed? Ask O Yes Print O No References