Question

Thirty-three items are randomly selected from a population of 350 items. The sample mean is 32, and the sample standard deviation 6. Develop a 90% confidence interval for the population mean. (Round the t-value to 3 decimal places. Round the final answers to 2 decimal places.)  

The confidence interval is between  and

Answer 1

Solution :

Given that,

t /2,df = 1.694

Margin of error = E = t/2,df * (s /n)

= 1.694 * (6 / 33)

Margin of error = E = 1.77

The 90% confidence interval estimate of the population mean is,

- E < < + E

32 - 1.77 < < 32 + 1.77

30.23 < < 33.77

The confidence interval is between 30.23 and 33.77