Use the following situation to answer questions 18 - 19. The math department wants to order class calculators for all their teachers. It is a lot of money to spend, so they want to make sure they are getting the best calculators out there. They select an SRS of 50 calculators from Company A and find that 3 of them do not work correctly. The select an SRS of 60 calculators from Company B and find that 5 calculators do not work correctly. 18) Which of the following represents a 90% confidence interval for a difference in proportions pA - PB, where pA is the proportion of Company A's calculators that are defective, and ps is the proportion of Company B's calculators that are defective? (A) -0.02 + 1.96 (0.12) (0.88) (0.14) (0.86) 50 60 (B) -0.02 + 1.96 (0.12) (0.88) (0.14) (0.86) 50 60 (C) -0.02 + 1.64 (0.12) (0.88) (0.14) (0.86) 50 60 (D) -0.02 + 1.64 (0.12) (0.88) + (0.14) (0.86) 50 60 (E) -0.02 + 1.64 (0.073) (0.927) 11019) Using a hypothesis test of Ho: pA - pp = 0 and HA: PA - PB # 0, they construct a 90% confidence interval of (-0.104, 0.057). Which of the following is the proper conclusion? (A) Because our null hypothesis of 0 is included in the interval, we would reject it. We have convincing evidence that Company A will have fewer defective calculators than Company B. (B) Because our null hypothesis of 0 is included in the interval, we would fail to reject it. We do not have convincing evidence that either calculator company is better than the other. (C) Because our confidence interval contains more negative probable values for the true difference, we have convincing evidence that Company A will have fewer defective calculators than Company B. (D) Because our confidence interval contains more negative probable values for the true difference, we do not have convincing evidence that either calculator company is better than the other. (F) We cannot draw a conclusion about the hypothesis test because it is inappropriate to use a confidence interval for a two-sided significance test