For an X-Bar Chart Where the Standard Deviation Is Known $\sqrt { n }$

Multiple Choice

For an x-bar chart where the standard deviation is known, the Upper Control Limit

A) is 3 . ? below the mean of sample means for a 3? control chart.
B) is 3 . ? above the mean of sample means for a 3? control chart.
C) is 3 . ?/ $\sqrt { n }$ below the mean of sample means for a 3? control chart.
D) is 3 . ?/ $\sqrt { n }$ above the mean of sample means for a 3? control chart.
E) Cannot be calculated unless the average range is known.