Suppose that we wish to estimate the population mean grade-point average (GPA) across all UVA undergraduate students. From a simple random sample of 50 undergraduate students, a 95% confidence interval for the population mean GPA is (2.9, 3.6).
Which of the following would decrease the margin of error of this confidence interval?
A: Increase the confidence level from 95% to 99%.
B: Increase the sample size from n = 50 to n = 100.
Both A and B would cause the margin of error to decrease.
Neither A nor B would cause the margin of error to decrease.
B: Increase the sample size from n = 50 to n = 100.
Increasing the sample size would lead to a smaller margin of error. The margin of error is inversely proportional to the square root of the sample size. Doubling the sample size from 50 to 100 would result in a smaller margin of error.