The IRS is concerned with improving the accuracy of tax information given by its representatives over the telephone. Previous studies involved asking a set of questions of a large number of IRS telephone representatives to determine the proportion of correct responses.$$ Historically, the average proportion of correct responses has been $71$ percent.$$ Recently, IRS representatives have been receiving more training. On April$26,$ the set of $25$ tax questions were again asked of $20$ randomly selected IRS telephone representatives. The proportions of correct answers$$ were:

$20,21,19,16,16,15,21,16,17,16,22,17,22,21,15,16,23,16,21,$ and $12.$

Part $2$

a$.$ What are the upper and lower control limits for the appropriate$$ p$-$chart for the$$ IRS? Use z$=.$

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enter your response here. $($Enter your responses rounded to four decimal places. If your answer for is$$ negative, enter this value as $0.$