Geometry | Unit 8 | Lesson 6: The Addition Rule | Practice Problems

Show how to apply the addition rule for the events “a child ticket is bought for a play” and “the play is performed in the afternoon.”

A biologist studies two different invasive species, purple loosestrife and the common reed, at sites in both wetland and coastal habitats. Purple loosestrife is present in 35% of the sites. Common reed is present in 55% of the sites. Both purple loosestrife and common reed are present in 23% of the sites. What percentage of the sites have purple loosestrife or common reed present?

• 12%

• 22%

• 67%

• 90%

What is Han’s mistake? Explain your reasoning. How does the addition rule account for this kind of mistake?

What is the probability that a student selected at random prefers to play tag at recess?

What is the probability that a student selected at random prefers to play tag or kickball at recess?

What is the probability that a student in class A selected at random prefers to play kickball at recess?

What is the probability that a student selected at random is in class B and prefers to play tag at recess?

How many outcomes are in the sample space?

What is the probability that an “o” is chosen?

What is the probability that a “k” is chosen?