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**Unformatted text preview: **LCL and UCL 6. Total number of defects is 72. Total number sampled is 144*20 = 2880. This makes p_bar = 72/2880 = 0.025 This makes q_bar = 1 – 0.025 = 0.975 The standard deviation is calculated using the formula This makes SD = 2.21 The control limits are calculated using UCL = p_bar + 3*sqrt(p_bar*q_bar/n_bar) LCL = p_bar - 3*sqrt(p_bar*q_bar/n_bar) Here n_bar = 144 Using this we have UCL = 0.064 LCL = -0.014 Since proportions of defects cannot be negative we shall take LCL as 0. P-Chart Based on the chart seen, the process is within control. None of the points have breached the UCL or LCL line. 7. Nmumber of days = 1 week = 7 days Sum of errors = 30 Average number of errors per day(C-bar) = Sum of errors / Number of days = 30/7= 4.29 UCL = C-bar + [3(Sqrt of C-bar)] = 4.29 + [3(Sqrt of 4.29)] = 4.29 + (3X2.071) = 4.29 + 6.213 = 10.503 LCL = C-bar - [3(Sqrt of C-bar)] = 4.29 - [3(Sqrt of 4.29)] = 4.29 - (3X2.071) = 4.29 - 6.213 = - 1.923 = 0 (as when the LCL is less than zero,it is considered as zero) 8....

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- Fall '14
- Luster