Processing new accounts at a bank is intended to average 10 minutes each. Five samples of seven observations (n) each have been taken.

 

Construct upper and lower control limits for both a mean ((X)) ̅ chart and a range chart ((R)) ̅:

 

UCLx ̅, LCLx ̅

 

and

 

UCLR ̅and LCLR ̅

	Sample Number
	Sample 1	Sample 2	Sample 3	Sample 4	Sample 5
1	10.20	10.30	9.70	9.90	10.25
2	9.90	9.80	9.90	10.30	10.00
3	9.80	9.90	9.90	10.10	9.70
4	10.10	10.40	10.10	10.50	10.70
5	9.90	9.80	9.90	10.30	10.00
6	9.80	9.90	9.90	10.10	9.70
7	10.10	10.40	10.10	10.50	10.70

Sample Size n	Mean Factor, A2	Upper Range, D4	Lower Range, D3
2	1.880	3.268	0.000
3	1.023	2.574	0.000
4	0.729	2.282	0.000
5	0.577	2.115	0.000
6	0.483	2.004	0.000
7	0.419	1.924	0.076
8	0.373	1.864	0.136
9	0.337	1.816	0.184
10	0.308	1.777	0.223
12	0.266	1.716	0.284