TABLE 17-2
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.
-Referring to Table 17-2, what is the numerical value of the center line for the p chart?
A) 0.53
B) 0.56
C) 0.63
D) 0.66

Question

TABLE 17-2
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. 
-Referring to Table 17-2, what is the numerical value of the center line for the p chart?
A) 0.53 
B) 0.56 
C) 0.63 
D) 0.66

Quizplus · Accepted Answer

The center line for a p chart is calculated as the overall proportion of successes in the data, which can be found by adding up the number of successes (votes for the incumbent) over all 8 days (536) and dividing by the total number of observations (800). This gives a proportion of 0.67, which is the center line for the p chart. However, in order to convert this proportion to a percentage, we multiply by 100 to get 67%. Therefore, the numerical value of the center line is 0.67 or 67%, which corresponds to choice B.

TABLE 17-2 A Political Pollster Randomly Selects a Sample of 100 Voters