merill lynch

# merill lynch - Calculate confidence intervals when a...

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Calculate confidence intervals when a population’s standard deviation is both know and unknown, for the below, show all work: 1. A sample of 81 observations is taken from a normal population. The sample mean is 40, and the sample standard deviation of 5. Determine the 95 percent confidence interval for the population mean. x-bar = 40, s = 5, n = 81 SE = s/ n = 5/ 81 = 0.555 The 95% CI for the population mean is given by x-bar ± 1.96 * SE = [40 ± 1.96 * 0.555] = [38.91, 41.09] 2. Merrill Lynch Securities and Health Care Retirement, Inc, are two large employers in down Toledo, OH. They are considering jointly offering child care for their employees. As a part of the feasibility study, they wish to estimate the mean weekly child-care cost of their employees. A sample of 10 employees who use child care reveals the following amounts spent last week. \$107, \$92, \$97, \$95, \$105, \$101, \$91, \$99, \$95, \$104 Develop a 90 percent confidence interval for the population mean. Interpret the result.

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## This note was uploaded on 01/05/2012 for the course 101 melissa jo taught by Professor Acc101 during the Spring '11 term at Aarhus Universitet.

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merill lynch - Calculate confidence intervals when a...

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