Assignment:
Sampling 4 pieces of precision-cut wire (to be used in computer assembly) every hour for the past 24 hours has produced the following results:
Hour Xbar R Hour Xbar R Hour Xbar R Hour Xbar R
1 3.15 0.76 7 3.15 0.53 13 3.21 0.80 19 3.31 1.66
2 3.10 1.13 8 2.65 1.08 14 2.83 1.31 20 2.99 1.14
3 3.12 1.48 9 2.92 0.76 15 3.12 1.01 21 2.65 1.03
4 3.49 1.31 10 2.85 1.28 16 2.74 0.55 22 3.28 0.41
5 3.17 1.22 11 2.93 1.17 17 2.86 1.43 23 2.94 1.63
6 2.86 0.37 12 3.07 0.35 18 2.84 1.34 24 2.54 0.92
Based on the sampling done, the control limits for 3-sigma x overbarx chart are (round all intermediate calculations to three decimal places before proceeding with further calculations):
Upper Control Limit (UCL Subscript x overbarUCLx)
Lower Control Limit (LCL Subscript x overbarLCLx)
Based on the x overbarx-chart, the wire cutting process has been
IN CONTROL or OUT OF CONTROL
The control limits for the 3-sigma R-chart are (round all intermediate calculations to three decimal places before proceeding with further calculations):
Upper Control Limit (UCL Subscript Upper RUCLR)
Lower Control Limit (LCL Subscript Upper RLCLR)
Based on the R-chart, the wire cutting process has been
IN CONTROL or OUT OF CONTROL