Why do exercises by hand?

This page provides some exercises that give practice with the steps used to evaluate a 95% confidence for the difference between two proportions. Although you are encouraged to use computer software to evaluate confidence intervals in practical situations, there are important general principles in all of the steps, so it is worthwhile to try a few exercises to ensure that you understand these general principles.

Exercises

Find 95% confidence intervals for the following problems.

Repeat with different questions until you feel confident with the method.