(Situation A) To construct a p-chart for a manufacturing process, 20 samples of size 100 were selected. The results areshown below:

$$\begin{array} { c c c c c c }
\hline \text { Sample } & \text { Sample Size } & \text { Defectives } & \text { Sample } & \text { Sample Size } & \text { Defectives } \
\hline 1 & 100 & 10 & 11 & 100 & 8 \
2 & 100 & 8 & 12 & 100 & 8 \
3 & 100 & 9 & 13 & 100 & 5 \
4 & 100 & 6 & 14 & 100 & 9 \
5 & 100 & 7 & 15 & 100 & 7 \
6 & 100 & 3 & 16 & 100 & 9 \
7 & 100 & 8 & 17 & 100 & 11 \
8 & 100 & 6 & 18 & 100 & 4 \
9 & 100 & 11 & 19 & 100 & 6 \
10 & 100 & 10 & 20 & 100 & 8 \
\hline
\end{array}$$
-Calculate the centerline used in constructing a p-chart.
A) .0706
B) .0532
C) .0765
D) .0266

Question

(Situation A) To construct a p-chart for a manufacturing process, 20 samples of size 100 were selected. The results areshown below:

$$\begin{array} { c c c c c c } 
\hline \text { Sample } & \text { Sample Size } & \text { Defectives } & \text { Sample } & \text { Sample Size } & \text { Defectives } \
\hline 1 & 100 & 10 & 11 & 100 & 8 \
2 & 100 & 8 & 12 & 100 & 8 \
3 & 100 & 9 & 13 & 100 & 5 \
4 & 100 & 6 & 14 & 100 & 9 \
5 & 100 & 7 & 15 & 100 & 7 \
6 & 100 & 3 & 16 & 100 & 9 \
7 & 100 & 8 & 17 & 100 & 11 \
8 & 100 & 6 & 18 & 100 & 4 \
9 & 100 & 11 & 19 & 100 & 6 \
10 & 100 & 10 & 20 & 100 & 8 \
\hline
\end{array}$$
-Calculate the centerline used in constructing a p-chart.
A) .0706
B) .0532
C) .0765
D) .0266

Quizplus · Accepted Answer

The centerline for a p-chart is calculated as the average proportion of defectives across all samples. Sum the defectives (10+8+9+6+7+3+8+6+11+10+8+8+5+9+7+9+11+4+6+8 = 149) and divide by the total number of items inspected (20 samples * 100 = 2000). The centerline is 149/2000 = 0.0745.

(Situation A) to Construct a P-Chart for a Manufacturing Process