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A simple random sample of 80 items resulted in a sample mean of 90. The population standard deviation is a = 5. (a) Compute the 95% condence interval for the population mean. (Round your answers to two decimal places.) S to S (In) Assume that the same sample mean was obtained from a sample of 160 items. Provide a 95% confidence interval for the population mean. (Round your answers to two decimal places.) |:|t|:| (c) What is the effect of a larger sample size on the interval estimate? 0 A larger sample size provides a smaller margin of error. 0 A larger sample size provides a larger margin of error. 0 A larger sample size does not change the margin of error. For a 1' distribution with 19 degrees of freedom, find the area, or probability, in each region. {Round your answers to three decimal places.) (a) to the right of .328 (b) to the left of1.}'29 (c) to the left of 2.093 (d) to the right of 2.539 (e) between 1.328 and 1.328 (f) between 2.093 and 2.093 Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. A sample of 68 weekly reports showed a sample mean of 19.5 customer contacts per week. The sample standard deviation was 4.2. Provide a 90% confidence interval for the population mean number of weekly customer contacts for the sales personnel. (Round your answers to two decimal places.) contacts/week to contacts/week Provide 95% confidence interval for the population mean number of weekly customer contacts for the sales personnel. (Round your answers to two decimal places.) contacts/week to contacts/week