Assume that a sample is used to estimate a population mean μ . Find the 90% confidence interval for a sample of size 64

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Assume that a sample is used to estimate a population mean μ .
Find the 90% confidence interval for a sample of size 64 with a
mean of 39.9 and a standard deviation of 18.7. Enter your answer as
an open-interval (i.e., parentheses) accurate to one decimal place
(because the sample statistics are reported accurate to one decimal
place). 90% C.I. = Answer should be obtained without any
preliminary rounding. However, the critical value may be rounded to
3 decimal places.