Answer Happy

Sampling 4 pieces of​ precision-cut wire​ (to be usedin computer​ assembly) every hour for the past 24 hours hasproduced the following​ results:
                                                                                                                                                       
Hour
x
R
Hour
x
R
Hour
x
R
Hour
x
R
1
3.15​"
0.65​"
7
3.15​"
0.48​"
13
3.21​"
0.85​"
19
3.31​"
1.66​"
2
3.00
1.23
8
2.75
1.18
14
2.83
1.36
20
2.79
1.09
3
3.22
1.48
9
3.12
0.71
15
3.12
1.11
21
2.75
1.03
4
3.49
1.31
10
2.75
1.33
16
2.94
0.45
22
3.38
0.51
5
3.17
1.17
11
2.83
1.17
17
2.76
1.38
23
3.04
1.58
6
2.86
0.42
12
2.97
0.40
18
2.64
1.34
24
2.74
0.92
Based on the sampling​ done, the control limits for​3-sigma x chart are ​(round all intermediatecalculations to three decimal places before proceeding with further​calculations)​: