Author:
Christine Farr

http://theperfecthomework.com/a-sample-of-144-cans-of-coffee-showed-an-average-weight-of-16-ounces/

1. A sample of 144 cans of coffee showed an average weight of 16 ounces. The standarddeviation of the population is known to be 1.44 ounces. Construct a 68.26% confidence intervalfor the mean of the population.2. A sample of 144 cans of coffee showed an average weight of 16 ounces. The standarddeviation of the population is known to be 1.44 ounces. Construct a 95.44% confidence intervalfor the mean of the population.3. A random sample of 81 credit sales in a department store showed an average sale of $68.00.From past data, it is known that the standard deviation of the population is $27.00. Construct a95% confidence interval of the population mean.4. A random sample of 81 airline pilots had an average yearly income of $99,400 with astandard deviation of $18,000. Build a 95% confidence interval for the average yearly income ofall pilots.5. The average monthly electric bill of a random sample of 100 residents of a city is $90 with astandard deviation of $24. Construct a 90% confidence interval for the mean monthly electricbills of all residents.6. The average monthly electric bill of a random sample of 100 residents of a city is $90 with astandard deviation of $24. Construct a 95% confidence interval for the mean monthly electricbills of all residents.7. A sample of 64 students from a large university is taken. The average age in the sample was22 years with a standard deviation of 6 years. Construct a 95% confidence interval for theaverage age of the population.8. A researcher is interested in determining the average number of years employees of acompany stay with the company. If past information shows a standard deviation of 7 months, what size sample should be taken so that at 95% confidence the margin of error will be 2months or less?9. In a sample of 400 individuals, 200 indicated they are Democrats. Develop a 95% confidenceinterval for the proportion of people in the population who are Democrats.10. In a random sample of 400 registered voters, 120 indicated they plan to vote for CandidateA. Determine a 95% confidence interval for the proportion of all the registered voters who willvote for Candidate A.

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