Mary is planning to survey a sample of women to find out how much money the average woman spent on lipstick last year. What sample size will she need, if she wants to be 95% confident that her sample mean is no more than $4 away from the population mean, and assuming a standard deviation of $20? A. 100

The required sample size = 97

Step-by-step explanation:

If prior population standard deviation is known, then the minimum sample size can be computed as:

,where z* = critical z-value

= population standard deviation

E = Margin of error

As per given,

Critical value for 95% confidence = 1.96

Hence, the required sample size = 97

the correct answer is 5 6 and 7

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step-by-step explanation: