For Exercise 4.54, see page 195; for 4.55, see page 197; for 4.56, see page 198; for 4.57 and 4.58, see pages 198199; for 4.59 and 4.60, see page 200; and for 4.61, see page 202.

Question 4.59

4.59 What rule did we use?

In Example 4.20, we calculated . What rule did we use for this calculation? Explain why this rule applies in this setting.

4.59

Rule 3. Addition rule for disjoint events. It applies in this setting because a student can’t be in more than one age group, so the four age groups are disjoint.