TABLE 18-2
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
$\begin{array}{cc}
\hline\text { Sample }&\text { Number Favoring}\
\text { (Day)}& \text { Incumbent Candidate }\
\hline1 & 57 \
2 & 57 \
3 & 53 \
4 & 5 1 \
5 & 5 5 \
6 & 6 0 \
7 &5 6 \
8 & 5 9\
\hline
\end{array}$

-Referring to Table 18-2, what is the numerical value of the center line for the p chart?
A) 0.63
B) 0.53
C) 0.66
D) 0.56

Question

TABLE 18-2 
A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.
 $\begin{array}{cc}
\hline\text { Sample }&\text { Number Favoring}\
\text {  (Day)}& \text { Incumbent Candidate }\ 
\hline1 & 57 \
2 & 57 \
3 & 53 \
4 & 5 1 \
5 & 5 5 \
6 & 6 0 \
7 &5 6 \
8 & 5 9\
\hline
\end{array}$

-Referring to Table 18-2, what is the numerical value of the center line for the p chart?
A) 0.63
B) 0.53
C) 0.66
D) 0.56

Quizplus · Accepted Answer

The center line for a p chart is the average proportion of successes. Here, it is the average number of voters favoring the incumbent over the total number of voters sampled. The total number favoring is 448, and the total number sampled is 800. Thus, the center line is 448/800 = 0.56.

TABLE 18-2 a Political Pollster Randomly Selects a Sample

TABLE 18-2
a Political Pollster Randomly Selects a Sample