1. Warm Up – 4/31 - Thursday
In a recent poll of 100 people, 40 people said they
were democrats, 35 people said they were republican, and
25 said they were independent. 25 of the democrats were
women, 15 of the republicans were women and, 10 of the
independents were women.
Find the probability that if you randomly select a name from
those polled:
It is a woman
It is a woman or a democrat
It is a man or an independent
Find the probability of pulling a woman’s name,
replacing it, then drawing a man’s name.

2. Tree Diagrams
When dealing with compound events, it is often useful to use something called a tree diagram.

3. Tree Diagrams
A tree diagram shows the branching possibilities of a situation.

4. Using Tree Diagrams to find probability
If I multiply down the branches I get the probability of compound events.

5. Example #2

6. Example #2 - Solution
The probability of getting 2 heads, we multiply down the branches: 1 2 ∙ 1 2 = 1 4 =25%

7. Example #3

8. Example #3 - Solution

9. Example #4

10. Example #3 - Solution
Notice our second choice is all dependent probability from the first choice.

11. Warm Up – 4/30 - Wednesday
A) Find the probability that a randomly selected customer
ordered a sandwich with whole wheat.
B) Find the probability that a randomly selected customer
Ordered Landen’s club on sourdough.