Question

Suppose it is desired to compare the proportion of male and female students who voted in the last presidential election. We decide to randomly and independently sample 1000 male and 1000 female students and ask if they voted or not. A printout of the results is shown below. Hypothesis Test - Two Proportions Sample Size Successes Proportion Males 1000 475 0.47500 Females 1000 525 0.52500 Difference -0.05000 Null Hypothesis: p1 = p2 Alternative Hyp: p1 ≠ p2 SE (difference) 0.02236 Z (uncorrected) -2.24 P 0.0253 95% Confidence Interval of Difference -0.09377 < p1-p2 < -0.00623 Which of the following statements is supported by the printout? We are 95% confident the proportion of all males who voted in the last presidential election equals the proportion of all females who voted in the last presidential election. We are 95% confident the proportion of all males who voted in the last presidential election is less than the proportion of all females who voted in the last presidential election. At the 95% confidence level, we cannot determine which proportion is larger. We are 95% confident the proportion of all females who voted in the last presidential election is less than the proportion of all males who voted in the last presidential election.

Answer 1

Given that the proportion of males is p1 and proportion of females is p2

Confidence interval for proportion difference p1 - p2 = (-0.09377, -0.00623))

Lower limit and upper limit for the confidence interval are negative, which means that the second proportion is larger than first proportion.

This tells us that the proportion of females is higher than proportion of males.

therefore, option B is correct answer

We are 95% confident the proportion of all males who voted in the last presidential election is less than the proportion of all females who voted in the last presidential election