quality tools

profileRami55
case_01_x-bar_and_r-s__chart.xls
Home>Business & Finance homework help>Operations Management homework help>quality tools

Sheet1

Computer upgrades have a normal time of 80 minutes.
Samples of 5 observations each have been taken, and the results are as listed. n=5
A. Construct X-Bar and R control chart x bar- avrge
B. Decide if this process is in control. n=5 n=5
C. If the customer requires the time falls in the rage of (72,88), find Cp. Range Chart D4=2.114 D3=0 X bar chart A2=0.577
Range Center Ucl LCL Xbar Center UCL LCL
1 79.20 78.80 80.00 78.40 81.00 2.60 1.77 3.751 0 79.48 80.27 81.29 79.24
2 80.50 78.70 81.00 80.40 80.10 2.30 1.77 3.751 0 80.14 80.27 81.29 79.24
3 79.60 79.60 80.40 80.30 80.80 1.20 1.77 3.751 0 80.14 80.27 81.29 79.24
4 78.90 79.40 79.70 79.40 80.60 1.70 1.77 3.751 0 79.60 80.27 81.29 79.24
5 80.50 79.60 80.40 80.80 78.80 2.00 1.77 3.751 0 80.02 80.27 81.29 79.24
6 79.70 80.60 80.50 80.00 81.10 1.40 1.77 3.751 0 80.38 80.27 81.29 79.24
7 79.91 80.60 80.33 80.71 80.04 0.80 1.77 3.751 0 80.32 80.27 81.29 79.24
8 79.96 80.93 80.33 80.95 79.94 1.01 1.77 3.751 0 80.42 80.27 81.29 79.24
9 80.02 81.26 80.33 81.19 79.83 1.42 1.77 3.751 0 80.53 80.27 81.29 79.24
10 80.07 81.59 80.33 81.42 79.73 1.85 1.77 3.751 0 80.63 80.27 81.29 79.24
11 80.12 81.91 80.33 81.66 79.63 2.29 1.77 3.751 0 80.73 80.27 81.29 79.24
12 80.17 82.24 80.33 81.90 79.53 2.72 1.77 3.751 0 80.83 80.27 81.29 79.24

Sheet1
Range
Center
Ucl
LCL

Sheet2
Xbar
Center
UCL
LCL

Sheet3

X Bar And R Control chart
1. Establish sampling plane(sample size n)
2-Collect samples (randmoly)
3- Construct R(range) chart.
1) Calclate Range =Max-Min
2) Center of R chart = Average (Ranges)
3) Find Factor D4 and D3 from" Factor" Table
4) Ucl = D4* center/ LCL=D3*cnter
5) Plot R chart
4) Construct X bar ( average/ mean) chart.
1) Calclate X bar = average ( obsrvation)
2) Center of x bar chart = Average of (x bar)
3) Find Factor A2 from" Factor" Table
4) Ucl = center of x bar chart+A2*center of R chart
LCL= center of X ba chat -A2* center of R chart
5) Plot R chart
5. interpret the control chart
Computer upgrades have a normal time of 80 minutes.
Samples of 5 observations each have been taken, and the results are as listed. n=5
A. Construct X-Bar and S control chart x bar- avrge
B. Decide if this process is in control.
C. If the customer requires the time falls in the rage of (72,88), find Cp. Range Chart B4= 2.089 B3=0.000 X bar chart A3=1.427
S Center Ucl LCL Xbar Center UCL LCL
1 79.20 78.80 80.00 78.40 81.00 1.04 0.74 1.554 0 79.48 80.27 81.33 79.21
2 80.50 78.70 81.00 80.40 80.10 0.87 0.74 1.554 0 80.14 80.27 81.33 79.21
3 79.60 79.60 80.40 80.30 80.80 0.53 0.74 1.554 0 80.14 80.27 81.33 79.21
4 78.90 79.40 79.70 79.40 80.60 0.63 0.74 1.554 0 79.60 80.27 81.33 79.21
5 80.50 79.60 80.40 80.80 78.80 0.81 0.74 1.554 0 80.02 80.27 81.33 79.21
6 79.70 80.60 80.50 80.00 81.10 0.54 0.74 1.554 0 80.38 80.27 81.33 79.21
7 79.91 80.60 80.33 80.71 80.04 0.35 0.74 1.554 0 80.32 80.27 81.33 79.21
8 79.96 80.93 80.33 80.95 79.94 0.50 0.74 1.554 0 80.42 80.27 81.33 79.21
9 80.02 81.26 80.33 81.19 79.83 0.66 0.74 1.554 0 80.53 80.27 81.33 79.21
10 80.07 81.59 80.33 81.42 79.73 0.83 0.74 1.554 0 80.63 80.27 81.33 79.21
11 80.12 81.91 80.33 81.66 79.63 1.00 0.74 1.554 0 80.73 80.27 81.33 79.21
12 80.17 82.24 80.33 81.90 79.53 1.17 0.74 1.554 0 80.83 80.27 81.33 79.21
Charts and S-Chart
The chart is more Sensitive Exam qustion IF n>=5 X bar and R chart n>7 X bar and S chart
Xbar
Center
UCL
LCL
X bar and Chart -S
S
Center
Ucl
LCL
chart-S