A Quality Analyst wants to construct a control chart based on four samples, each

from on processing lines, all producing the same product. For each sample, there are

five observations with regard to a particular quality variable. The results are presented

in the following table:

Samples

Observations	1	2	3	4
1	17.0	16.5	23.2	22.0
2	15.1	25.0	24.2	23.3
3	15.0	18.2	23.3	18.7
4	17.7	25.1	22.0	23.1
5	21.3	19.6	21.4	20.1
	Average 17.22	20.88	22.82	21.44

Suppose the standard deviation is 2.70, what are the upper and lower control limits

for the x-bar chart at the three sigma level (z=3)? Please show computation and steps.