A quality control program is being developed for batteries.The percent defective for these in the past has been 3%.If a sample size of 120 is taken, what would the 99.7% upper control chart limit be?
A)0.0812
B)0.0767
C)0.0611
D)0.0307

Question

Quizplus · Accepted Answer

The 99.7% upper control limit for a proportion can be calculated using the formula: UCL = p + Z√(p(1-p)/n), where p is the proportion of defectives (0.03), Z is the Z-value for 99.7% confidence (approximately 3 for three standard deviations from the mean in a normal distribution), and n is the sample size (120). Plugging in the values: UCL = 0.03 + 3√(0.03*0.97/120) ≈ 0.03 + 0.0467 = 0.0767.

A Quality Control Program Is Being Developed for Batteries