A random sample of 20 items is selected from a population. When computing a confidence interval for the population mean,what number of degrees of freedom should be used to determine the appropriate t-value?
A)20
B)19
C)21
D)25

Question

Quizplus · Accepted Answer

When computing a confidence interval for the population mean with a sample size of n=20, we should use n-1 degrees of freedom, which is 19. This is because we are estimating the population variance using the sample variance, which creates one less degree of freedom in the calculation.

A Random Sample of 20 Items Is Selected from a Population