1. A sample of 144 cans of coffee showed an average weight of 16 ounces. The standard deviation of the population is known to be 1.44 ounces. Construct a 68.26% confidence interval for the mean of the population. 2. A sample of 144 cans of coffee showed an average weight of 16 ounces. The standard deviation of the population is known to be 1.44 ounces. Construct a 95.44% confidence interval for 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 a 95% confidence interval of the population mean. 4. A random sample of 81 airline pilots had an average yearly income of $99,400 with a standard deviation of $18,000. Build a 95% confidence interval for the average yearly income of all pilots. 5. The average monthly electric bill of a random sample of 100 residents of a city is $90 with a standard deviation of $24. Construct a 90% confidence interval for the mean monthly electric bills of all residents. 6. The average monthly electric bill of a random sample of 100 residents of a city is $90 with a standard deviation of $24. Construct a 95% confidence interval for the mean monthly electric bills of all residents. 7. A sample of 64 students from a large university is taken. The average age in the sample was 22 years with a standard deviation of 6 years. Construct a 95% confidence interval for the average age of the population. 8. A researcher is interested in determining the average number of years employees of a company 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 2 months or less? 9. In a sample of 400 individuals, 200 indicated they are Democrats. Develop a 95% confidence interval 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 Candidate A. Determine a 95% confidence interval for the proportion of all the registered voters who will vote for Candidate A