A manager of a branch of a local bank wants to estimate the average amount held in a particular type of savings account at the bank. A sample of 30 depositors using this type of savings account is selected and the results indicate a sample average of $4,750 and a sample standard deviation of$1,200. A. Determine a 95% confidence interval for the mean account balance on this store's credit card. Note: t multiple should use 29 degrees of freedom and sample size of 30. B. What sample size would be needed to ensure that we could estimate the true mean account balance and have only 5 chances in 100 of being off by no more than $278?
Added by Nicholas F.
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We are given the sample mean ($\bar{x}$) as $4,750, the sample standard deviation (s) as $1,200, and the sample size (n) as 30. Show more…
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