Using this partial Z Table, how many units from a month’s production run are expected to not satisfy customer requirements for the following process? Upper specification limit: 7.2 Lower specification limit: 4.3 Mean of the process: 5.9 Standard Deviation: 0.65 Monthly production: 450 units
A. 3
B. 7
C. 10
D. 12
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how to get alpha from Z value? please explain
No response is right
For UCL=7.2
Z= (7.2-5.9)/0.65=2–> Alpha=1-0.9772= 0.0228–> number of defects: 450 * 0.0228 = 10
For LCL= 4.2
Z= (5.9-4.3)/0.65 =2.46–> Alpha = 0.007 –> number of defects: 450 * 0.007 = 3
Total number of defects= 10+3=13
I would say the response C is the correct one.
…maybe the larger nr of defects should be reported, which is in this case the one of ULC = 10.
can you please explain?
It should be D
For UCL=7.2
Z= (7.2-5.9)/0.65=2–> Alpha=1-0.9772= 0.0228–> number of defects: 450 * 0.0228 = 10
For LCL= 4.2
Z= (5.9-4.2)/0.65 =2.615–> Alpha = 0.0045 –> number of defects: 450 * 0.0045 = 2
Total number of defects= 10+2=12