Statistics calculated from a sample of 17 observations are: Σ, 2 =1277 ₁² = 103225 Provide the following, rounding your answers to two decimal places. (a) Find the sample mean. (b) What is the sample standard deviation? (c) Assume that the population distribution is normal. Find a 95% confidence interval for the population mean. ( 4) 1. 4.
In a sample of credit card holders the mean monthly value of credit card purchases was $210 and the sample variance was 51 ($ squared). Assume that the population distribution is normal. Answer the following, rounding your answers to two decimal places where appropriate. (a) Suppose the sample results were obtained from a random sample of 15 credit card holders. Find a 95% confidence interval for the mean monthly value of credit card purchases of all card holders. 4) (b) Suppose the sample results were obtained from a random sample of 19 credit card holders. Find a 95% confidence interval for the mean monthly value of credit card purchases of all card holders. 4 4) Before you answer (b) consider whether the confidence interval will be wider than or narrower than the confidence interval found for (a). Then check that your answer verifies this.
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