Jamison Kovach Supply Company manufactures paper clips and o

Jamison Kovach Supply Company manufactures paper clips and other office products. Although inexpensive, paper clips have provided the firm with a high margin profitability. Sample size is 50. Results are given for the last 10 samples. Sample Defectives 10 12 4 4 4 The type of control chart that is best to monitor this process is p - chart a) Establish the control limits to include 99.73% of the random variation in defectives. uCL-(enter your response as a number between 0 and 1, rounded to three decimal places)

Solution

Proportion of defectives, Pbar

= Total number of defectives / ( Sample size x Number of sample)

= ( 4 + 7 +3 + 5+5+5 +5 +4 +2 +12)/ ( 50 x 10 ) = 52/ 500 = 0.104

Sample size = n = 50

Z value for 99.73 % variation = NORMSINV ( 0.9973) = 2.7821

Upper control limit for P chart, UCLp

= Pbar + Zvalue x Square root ( Pbar x ( 1 – Pbar)/n)

= 0.104 + 2.7821 x Square root ( 0.104 x 0.896 /50)

= 0.104 +2.7821 x 0.0431

= 0.104 + 0.1199

= 0.2239 ( 0.224 rounded to 3 decimal places )

UCLp = 0.224

UCLp = 0.224