12.32.

(a) Explain carefully the difference between a probability of Type I error of 0.05 for a single comparison of two means and a multiple comparison error rate of 0.05 for comparing all pairs of means.

(b) In multiple comparisons following a one-way ANOVA with equal sample sizes, the margin of error with a 95% confidence interval for comparing each pair of means equals 10. Give three sample means illustrating that it is possible that group A is not significantly different from group B and group B is not significantly different from group C, yet group A is significantly different from group C.