A 95% confidence interval is found to be (24, 30). The sample standard deviation is 7.5, and the sample size is 25. If you wanted a smaller interval, what could you do?
A. Increase the standard deviation to 9
B. Increase the confidence level to 99.7%
C. Decrease the sample size to 20
D. Increase the sample size to 36
D. Increase the sample size to 36
Increasing the sample size will result in a smaller margin of error and a narrower confidence interval. This is because as the sample size increases, the standard error decreases and the estimate becomes more precise.