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Confidence interval for the population proportion

1. Ophelia O'Brien, VP of Consumer Credit of American First Banks (AFB), has implemented a 'fast feedback' to keep her informed of the default rate on personal loans at the AFB member banks. On each Friday, the default rate is calculated for a sample of 500 personal loans. Last Friday's sample contained 30 defaulted loans. The 95% confidence interval for the population proportion is _________.

0.046 to 0.074
0.039 to 0.081
0.043 to 0.077
0.028 to 0.060

2. An Employee Involvement Team is studying a problem of quality with an aluminum casting. Team members gather data on 400 castings and compiled the following table.

Discuss the team's findings. What can the team conclude from these data? What employment practices or other factors may explain the 'night shift problem?' What graphic depiction should the team choose for the presentation to their supervisors?

3. The eight employees of the Tuning Department and their "years of experience" are listed in the following table.

If a sample of two employees is selected without replacement, which of the following is not a possible value of the sample mean years of experience?

See attached file for full problem description.

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Solution Summary

Answers questions on 95% confidence interval for the population proportion, sample without replacement etc.