Question

In 2003 and 2017 a poll asked Democratic voters about their views on the FBI. In​ 2003, 42​% thought the FBI did a good or excellent job. In​ 2017, 64​% of Democratic voters felt this way. Assume these percentages are based on samples of 1200 Democratic voters.

1) Can we​ conclude, on the basis of these two percentages​ alone, that the proportion of Democratic voters who think the FBI is doing a good or excellent job has increased from 2003 to​ 2017? Why or why​ not?

Select one:

a. No. Although a lesser percentage is present in the​ sample, the population percentages could be the same or even reversed.

b. No. Since a greater percentage is present in the​ sample, we cannot conclude that a lesser percentage of Democratic voters who think the FBI is doing a good or excellent job is present in the population.

c. No. Although a lesser percentage is present in the​ sample, the population percentages could be the​ same, but could not be reversed.

d. Yes. Since a lesser percentage is present in the​ sample, a lesser percentage of Democratic voters who think the FBI is doing a good or excellent job is present in the population.

2) Construct a 95​% confidence interval for the difference in the proportions of Democratic voters who believe the FBI is doing a good or excellent​ job, p1−p2. Let p1 be the proportion of Democratic voters who felt this way in 2003 and p2 be the proportion of Democratic voters who felt this way in 2017.

Select one:

a. (0.39, 0.45)

b. (-0.259, -0.181)

c. (-0.24, -0.20)

d. (0.63, 0.65)

Answer 1

1)

Correct option : c. No. Although a lesser percentage is present in the​ sample, the population percentages could be the​ same, but could not be reversed.

2)

Correct option : b. (-0.259, -0.181)