7. Ten samples of 15 parts each were taken from an ongoing process to establish a p-chart for control. a. Develop a p-Chart for 95 percent confidence (1.96 standard deviation). b. Based on the plotted data points, what comments can you make

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Answer: Hello the table related to your question is attached below

answer:

a) attached below

b) The process is out of control because two ( 2 ) values from the defect rate table are out of the control limits at 95% as seen in the p-chart in question ( A )

Step-by-step explanation:

a) p-chart for 95% confidence

std = 1.96

Total defects = ∑ number of defective items in the sample = 10

number of samples = 10

sample size ( n ) = 15

The P value for the process is calculated as :

Total defects / ( number of sample * sample size )

= 10 / ( 15 * 10 ) = 10 / 150 = 0.067

standard deviation ( σ ) = [tex]\sqrt{\frac{p(1-p)}{n } } = \sqrt{\frac{0.067(1-0.067)}{15} }[/tex]  =  0.065

next we determine the limits ( i.e. upper and lower )

UCL = p + zSp = 0.067 + 1.96(0.065 ) = 0.194

LCL = p - zSp = 0.067 - 1.96(0.065) = -0.060 ≈ 0 ( because LCL ≠ negative)

attached below is the required p-chart

b) The process is out of control because two ( 2 ) values from the defect rate table are out of the control limits at 95% as seen in the p-chart in question ( A )

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