In a study of size 8 where the variance is unknown, the distribution that should be used to calculate confidence intervals is
A) a normal distribution
B) a t distribution with 7 degrees of freedom
C) a t distribution with 8 degrees of freedom
D) a t distribution with 9 degrees of freedom

Question

Quizplus · Accepted Answer

When the sample size is less than 30 and the population variance is unknown, we use a t distribution. The degrees of freedom for the t distribution is equal to the sample size minus one, which is 7 in this case. Therefore, the correct choice is B, a t distribution with 7 degrees of freedom.

In a Study of Size 8 Where the Variance Is