Determine the upper control limit

Determine the upper control limit (+3 standard deviation) for proportion defective when the average daily output is 1,335 units and the average fraction defective for last 3 months is 0.03%.

OPTIONS

• 0.09
• 0.044
• 0.55
• 0.03

ANSWER

0.044

EXPLANATION

For this question, we need p-control chart to compute the UCL The upper control limit is calculated by using: UCL = p-bar + (3 * sqrt (p-bar * (1-p-bar)/n)) UCL = 0.03 + (3 * sqrt (0.03 * (1-0.03)/1335)) UCL = 0.03 + (3 * sqrt ( 0.0291/ 1335)) UCL = 0.03 + (3 * 0.00467) UCL = 0.03 + 0.014