Question

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


If he uses upper and lower control limits of 22 and 18 ounces, on what day(s), if any, does this process appear to be out of control?

Answer 1

Answer:

1.Monday and Tuesday

2.none of the machines

3.23

4. 91.08 %----

5. 10.922 , 65.21