Business stats three questions to be answered

12.3 a, A random sample of 25 was drawn from a popu- 12.5 a. A statistics practitioner drew a random sample lation. The sample mean and standard deviation of 400 observations and found that & = 700 and are x = $10 and s = 125, Estimate a with 95% 5- 100, Estimate the population mean with confidence. 90% confidence. b. Repeat part (a) with n = 50. b. Repeat part (a) with a 95% confidence level. c. Repeat part (a) with * = 100. c. Repeat part (a) with a 99% confidence level. d. Describe what happens to the confidence inter- d. What is the effect on the confidence interval val estimate when the sample size increases. estimate of increasing the confidence level? 12.7 a. A statistics practitioner calculated the mean and standard deviation from a sample of 51. They are > = 120 and s = 15. Estimate the population mean with 95% confidence. b. Repeat part (a) with a 90% confidence level. c. Repeat part (a) with an 80% confidence level. d. What is the effect on the confidence interval estimate of decreasing the confidence level