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b.What is the margin of error at the 90% confidence level?
c.Construct a 95% confidence interval for the mean unit cost of the population if the sample unit cost is obtained from a random sample of 200 instead of 120.ad.Based on the results from a. and c., what can you say about the effect of a larger sample size on the length of the confidence interval at the same confidence level?5.A simple random sample of 50 items is taken from an inventory and the average unit cost on the items is $24.5. The population standard deviation is not known. Instead the sample standard deviation s is also calculated from the sample and equals to $12.5. (4 Points)a.Construct a 99% confidence interval for the mean unit cost of the populationx±ta2Sσnb.What is the margin of error at the 95% confidence level?
6.The average score on an employee satisfaction survey is found to be 3.7 (out of 5). The sample standard deviation is 1.25. These two statistics are calculated from a random sample of 30 employees in a mid-size professional firm. (4 Points1.With 95% confidence, what is the margin of error?)