1.A study conducted several years ago reported that 20 percent of public accountants changed companies within 2 years. The American Institute of CPAs would like to update the study. They would like to estimate the population proportion of public accountants who changed companies within 2 years with a margin of error of 2% and a 99% level of confidence. (Round your z value to 2 decimals. Round up your answers to the next whole number.)

a. To update this study, the files of how many public accountants should be studied?

SAMPLE SIZE=

b. How many public accountants should be contacted if no previous estimates of the population proportion are available?

SAMPLE SIZE=

2.

A survey of an urban university (population of 25,450) showed that 750 of 1,100 students sampled attended a home football game during the season. Using the 90% level of confidence, what is the confidence interval for the proportion of students attending a football game?

A.[0.6659, 0.6941]

B.[0.7510, 0.8290]

C. [0.6592, 0.7044]

D. [0.6795, 0.6805]

3.Suppose 1,680 of 2,000 registered voters sampled said they planned to vote for the Republican candidate for president. Using the 0.95 degree of confidence, what is the interval estimate for the population proportion (to the nearest 10th of a percent)?

A. 82.4% to 85.6%

B.73.4% to 90.2%

C.80.7% to 87.3%

D.81.9% to 86.1%