Question 727231
The population variance is unknown. So the population standard deviation is also unknown (since variance = (standard deviation)^2)


So because the the population standard deviation is unknown AND the sample size n is less than 30, this means that you must use the T distribution.


In this case, you would use a T distribution with degrees of freedom (df) of...


df = n-1


df = 13-1


df = 12


So the answer is <font color="red">B)	a t distribution with 12 degrees of freedom</font>