Assume That for an In-Control Process, the Random Variable of Interest

Multiple Choice

Assume that for an in-control process, the random variable of interest X has a normal distribution with mean value $\mu$ and standard deviation $\sigma$ . If $\bar { X }$ denotes the sample mean for a random sample of size n selected at a particular time, then

A) $E ( \bar { X } ) = \mu$
B) $\sigma _ { \bar { x } } = \sigma / \sqrt { n }$
C) $\bar { X }$
Has a normal distribution.
D) All of the above are true.
E) None of the above are true.