Question

Assume that a sample is used to estimate a population mean μ. Find the 99% confidence interval for a sample of size 45 with a mean of 20.1 and a standard deviation of 11.1. Enter your answer as an open-interval (i.e., parentheses) accurate to 3 decimal places.

99% C.I. =

Answer 1

Solution :

t _/2,df = 2.692

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

= 2.692 * (11.1 / 45)

Margin of error = E = 4.454

The 99% confidence interval estimate of the population mean is,

- E < < + E

20.1 - 4.454 < < 20.1 + 4.454

15.646 < < 24.554

99% C.I. = (15.646 , 24.554)