Use the given process data to construct a control chart for p. A drugstore considers a wait of more than 5 minutes to be a defect. Each week 100 customers are randomly selected and timed at the checkout line. The numbers of defects for
20 consecutive weeks are given below. $$\begin{array} { l l l l l l l l l l l l l l l l l l l l }
4 & 4 & 5 & 5 & 5 & 5 & 5 & 6 & 6 & 6 & 6 & 12 & 6 & 6 & 6 & 7 & 6 & 7 & 8 & 7
\end{array}$$ What is the value of the upper control limit?
A) 0.0622
B) 0.0783
C) 1
D) 6.2

Question

Use the given process data to construct a control chart for p. A drugstore considers a wait of more than 5 minutes to be a defect. Each week 100 customers are randomly selected and timed at the checkout line. The numbers of defects for
20 consecutive weeks are given below. $$\begin{array} { l l l l l l l l l l l l l l l l l l l l } 
4 & 4 & 5 & 5 & 5 & 5 & 5 & 6 & 6 & 6 & 6 & 12 & 6 & 6 & 6 & 7 & 6 & 7 & 8 & 7
\end{array}$$ What is the value of the upper control limit?
A) 0.0622
B) 0.0783
C) 1
D) 6.2

Quizplus · Accepted Answer

The upper control limit for a p-chart is given by p + 3√(p(1-p)/n), where p is the sample proportion and n is the sample size. In this case, p = 0.06 and n = 100, so the upper control limit is 0.06 + 3√(0.06(1-0.06)/100) = 0.0783.