Critical Thinking: Different Confidence Levels

(a) Suppose a 95% confidence interval for the difference of means contains both positive and negative numbers. Will a 99% confidence interval based on the same data necessarily contain both positive and negative numbers? Explain. What about a 90% confidence interval? Explain.

(b) Suppose a 95% confidence interval for the difference of proportions contains all positive numbers. Will a 99% confidence interval based on the same data necessarily contain all positive numbers as well? Explain. What about a 90%

confidence interval? Explain.

AppendixLO1