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**sinlee2010** Please help me solve this problem. I need to know what is the correct formula in order to solve the problem. Thanks

Use the given confidence level and sample data to find (a) the margin error E and (b) a confidence interval for estimation the population mean u.

Times between using a dishwasher: 90% confidence or 1.645 (critical value); n = 25, x = 5.24 sec, the population is normally distributed, and o is known to be 2.50 sec. Note: I was unable to put the minus sign over the x symbol.

Sin