1. Under what conditions should we use a z formula when dealing with the difference in two means? A t formula?
2. Are the conclusions from this section useful and reliable if the populations for the measurements being studied are not normally distributed?
3. What is the key difference between the t Formula 10.3 and the t Formula 10.4 to test the difference in means when population variances are unknown? Explain under what conditions each formula should be used.
4. Explain the relationship between sample sizes and the width of the confidence interval for the difference in two population means when population variances are unknown and equal.