Question

Calculate the minimum sample size required in order to make a 95% confidence interval for a population mean when sigma = 4.5 and the margin of error is to be no more than 1.2. Show work to receive full credit .

Answer 1

Since, population standard deviation = =4.5 is known, we will use z score to find the critical value.

Confidence level =95%

Corresponding z score =1.96= z (from table)

Margin of error =MOE= 1.2 (less than or equal to 1.2)

Let n be the required sample size.

By problem, it is given that,

The minimum sample size required in order to make a 95% confidence interval for a population mean when sigma = 4.5 and the margin of error is to be no more than 1.2 is 55. (Answer)