17. Formulas for estimating a population average when sigma is known involving using the Distribution, while formulas for estimating a population average when sigma is unknown involves and formulas for estimating population proportions involve a distribution. A. T, Z, left -skewed B. Z, T, Z C. Right skewed, Z, Uniform D. T, Z, Chebychev E. None of the above are correct 18. A pizza shop owner wishes to find the 92% confidence interval of the true mean cost of a large plain pizza. How large should the sample be if she wishes to be accurate to within $0.15? A previous study showed that the standard deviation of the price was $0.26 A)3 B)9 C)6 D) 1 E) information about the variance must be given to solve the problem 19. Determine the Z score(s) for 95% confidence A. 1.96 B +-1.96 C 2.58 D. +-1.65 E. +-1.65 20. Determine the Z score(s) for 90% confidence A. 1.96 B +-1.65 C 2.58 D. +-1.96 E. -1.65 21. Determine the Z score(s) for 92% confidence A. 1.41 B +-1.75 C -1.75 D. 2.05 E. none of the above 22. Determine the Z score(s) for 84% confidence A. -1.41 B +-1.41 C +-2.00 D. 1.96 E. 0.99