A quality analyst wants to construct a sample mean chart for controlling a packaging process. He knows from past experience that whenever this process is in control, package weight is normally distributed with a mean of 20 ounces and a standard deviation of two ounces. Each day last week, he randomly selected four packages and weighed each

Day	Weight (ounces)
Monday	23	22	23	24
Tuesday	23	21	19	21
Wednesday	20	19	20	21
Thursday	18	19	20	19
Friday	18	20	22	20

What is the mean of the sampling distribution of sample means when this process is in control?

Group of answer choices

18 ounces

19 ounces

20 ounces

21 ounces

22 ounces