8. Determine the sample size if the confidence level is 95%, the variable of interest represents 30% of the population, and the accepted margin of error is 5%.

9. Determine the size of the sample to study the opinion of university professors in companies in the capital. Estimate that there are a total of 2,100 professors and assume that you limit your research to the eastern area of the city. With a total of 458 teachers, assume a level of 95% reliability and a margin of error of 5 percent.

11. A product X is made 15,000 units per month in factory 1, out of a total of 45,800 that are made in all the factories of the corporation. Assume that the confidence level is 95 percent, and the accepted margin of error is 0.05. Determine the sample size.

12. Determine the sample size from the previous exercise assuming the sample will be drawn from a single-day production of 900 at Factory 1.

13. Determine the sample size to survey the customers of a store in a shopping center if there are 500 customers of the 11,000 in all the stores of the corporation. Assume that the confidence level is 95 percent and the accepted margin of error is 0.05.

14. Determine the sample size from the previous exercise assuming that the sample of customers will be taken from one of the departments in the store where there are a total of 200 customers.