1. Pettit 9-2 Notes D7 : Compute probabilities using tree diagrams
9-2 Tree Diagrams (pgs )
D7 : Compute probabilities using tree diagrams

2. There are 4 different outcomes for the colors and sizes of the watch.
Example 1
A certain type of watch comes in brown or black and in a small or large size. Find the number of color-size combinations that are possible.
Make a tree diagram to show the sample space. Then give the total number of outcomes.
Sample Space
Size
Color
small
brown, small
brown
large
brown, large
small
black, small
black
large
black, large
There are 4 different outcomes for the colors and sizes of the watch.

3. Example 2
Suppose Pablo tosses 3 coins. Find the probability of all three coins landing on tails.
Make a tree diagram to show the sample space. Then give the total number of outcomes, and the probability of all three landing on tails.
Sample Space
Coin #3
Coin #2
Coin #1
heads
heads, heads, heads
heads
tails
heads, heads, tails
heads
heads
heads, tails, heads
tails
tails
heads, tails, tails
heads
tails, heads, heads
heads
tails
tails
tails, heads, tails
tails
heads
tails, tails, heads
tails
tails, tails, tails
There are 8 different outcomes for the coin toss The probability of all three coins landing on heads is .

4. You try…
A family has two children. Draw a tree diagram to show the sample space of the children’s genders. Then determine the probability of the family having two girls.