The IRS is concerned with improving the accuracy of tax info given by its reps over the phone. Previous studies involved asking a set of 25 questions of a large number of IRS telephone reps to determine the proportion of correct responses. Historically, the average proportion of correct responses has been 71%. Recently, the set of 25 questions were again asked of 20 randomly selected reps. The proportions of correct answers were:
15, 15, 19, 17, 15, 17, 21, 13, 17, 13, 24, 16, 23, 16, 21, 20, 23, 19, 21, and 16.
A) What are the upper and lower control limits for the appropriate p-chart for the IRS? Use z = 3
The UCLp = ___
The LCLp = ___