9.2 Tree Diagram

Use tree diagrams to count outcomes and find probabilities

Sarah has a date and is trying to decide what to wear. She has 3 tops and 4

skirts. How many options does Sarah have?

• Less than 7

• Exactly 7

• More than 7

Sarah has a date and is trying to decide what to wear. She has 3 tops and 4

skirts. How many options does Sarah have?

How can we organize this information?

• Let’s call each shirt A, B, and C and each skirt 1, 2, 3, and 4.

What is the probability she will wear shirt C and skirt 1?

What is a fair game?

Match/No-Match game

• Players take turns spinning a spinner like the one shown here.

• On each turn, a player spins

Twice. If both spins land on the

Same color (a match), then

Player A scores 1 point. If the two spins land on different colors (a no-match), then Player B scores 2 points.

The player with the most points after 24 spins wins.

Work with a partner

• List all the outcomes of a turn (2 spins)

• What is the probability of a match and a no-match?

• Are the outcomes equally likely?

• Is the game fair? If not, can the rules be changed so that it is fair?

You toss 3 pennies. What is the probability that all 3 are heads?

1. P(3 tails)

2. P(exactly 2 heads)

3. P(at least 1 tail)

You toss 3 pennies.

A bag contains 1 red marble and 1 white marble. A second bag contains 1 red, 1 white, and 1 yellow marble. How

many outcomes are possible if a marble is picked from each bag?

How many lunches can be made from a choice of hot dog or burger, lemonade

or tea, and pie, cake, or brownies.

With a partner work the handout on your own paper.

Exit Pass

• How are tree diagrams useful?

• Do you think there is a shortcut?

Homework

• p 376: 7-17, 24