QUESTION 9

National Science Foundation is estimating the average total salary of full professors in the math department. Data were randomly collected from 20 professors and the 95% confidenceinterval for the mean was calculated to be ($95,201, $108,030). What additional assumption is necessary for this confidenceinterval to be valid?

	A.	None. The Central Limit Theorem applies.
	B.	The sample standard deviation is less than the degrees of freedom.
	C.	The population of total salaries of full professors in math is approximately normally distributed.
	D.	The distribution of the sample means is approximately normal.