Question

It is known that the standard deviation for the number of minutes women spend applying makeup everyday is 17 minutes if you want to construct a 95% confidence interval for the mean amount of time women spend applying make up with a margin of error of no more than 5 mins. At least how many women must you survey
95% = mean ± 1.96SEm

1.96 SEm ≤ 5

SEm = SD/√n

I'll let you do the calculations.

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