A research firm needs to estimate within 3% the proportion of junior executives leaving large manufacturing companies within three years. A 0.95 degree of confidence is to be used. Several years ago, a study revealed that 26% of junior executives left their company within three years. To update this study, how many junior executives should be surveyed?

Multiple Choice

• 822

• 725

• 707

• 1,010

  A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spent studying per week. Assuming a population standard deviation of six hours, what is the required sample size if the error should be less than an hour with a 95% level of confidence?

  Multiple Choice

• 360

• 465

• 34

• 219

  A university surveyed recent graduates of the English department for their starting salaries. One hundred and ninety-six graduates returned the survey. The average salary was $26,800. The population standard deviation was $1,650. What is the 95% confidence interval for the mean salary of all graduates from the English department?

  Multiple Choice

• [$26,569; $27,031]

• [$26,788; $26,812]

• [$26,604; $26,996]

• [$25,150; $28,450]