Given the following process control data for a normally distributed nuati... hree samples of size four each): If the process is known to have a mean of 15 and a standard deviation of 3 , what is the mean of the sampling distribution of sample means for whenever this process is under control? The standard deviation? Given the following process control data for a normally distributed nuati... hree samples of size four each): If the process is known to have a mean of 15 and a standard deviation of 3 , what is the mean of the sampling distribution of sample means for whenever this process is under control? The standard deviation