Question

A random sample is taken and the sample size is 25. the sample is normally distributed, the sample mean is 80, and the standard deviation is 5.5. find a 90% confidence interval for the population mean.

Answer 1

The 90% confidence interval for the population mean is 78.1905<x<81.8095

Confidence interval

The formula for calculating the confidence interval is expressed as:

CI = x ± z*s/√n

Given the following parameters

mean "x" = 80

z = 1.645

s = 5.5

n = 25

Substitute

CI = 80 ± 1.645*5.5/√25

CI = 80 ± 1.8095

CI = {78.1905, 81.8095}

Hence the 90% confidence interval for the population mean is 78.1905<x<81.8095

Learn more on confidence interval here: brainly.com/question/2141785

#SPJ1