A quality analyst wants to construct a control chart for controlling a packaging process. Each day last week, he randomly selected four packages and weighed each. The population standard deviation is 2.15. The data from that activity appear below.

	Weight
Day	Package 1	Package 2	Package 3	Package 4
Monday	32	26	24	34
Tuesday	18	28	27	22
Wednesday	33	17	25	30
Thursday	18	22	26	17
Friday	28	20	24	19

a. What is the mean of all the sample means? [ Select ] ["20.62", "19.11", "20.63", "22.05", "24.50"]

b. Calculate upper and lower 3-sigma x-bar chart control limits that allow for natural variations. [ Select ] ["25.70, 18.41", "21.45, 18.65", "20.6, 2.82", "15.53, 2.4", "27.73, 21.28"]

c. Based on the x-bar chart, is this process in control? [ Select ] ["yes", "no", "possibly based on acceptable variation", "cannot determine based on the information given"]

d. Calculate upper and lower limits for R-chart. [ Select ] ["15.89, 0", "26.82, 0", "11.41, 0", "24.65, 0", "27.54, 0"]

e. Is the range chart in control? [ Select ] ["no", "cannot determine based on the information given", "based on dispersion in the process, no", "yes"]