- Conditional Probability
- Probability Trees
- Homework Assign.
- Question
Conditional Probability
Ex. What is the probability of choosing a green and then a purple without replacing the green?
2 red
4 green
5 purple
Total of 11
Choosing a green - 4/11
Choosing a purple without replacing the green - 5/10 The total has been changed from 11 to 10 because the green was not replaced
Conditional probability requires to multiplyMultiply 4/11 times 5/10
= 20/110
Simplify 20/110 = 2/11
Answer: 2/11
Probability Trees
Ex:
- If it is raining, Johnny will drive
- Johnny drives 40% of the time when it is no raining
- It rains 15% of the time
To make it simplier use decimals
So if 15% of the time it rains then 85% of the time is dry
From that 85% of dry weather, Johnny drives 40% of the time while the other 60% he walks
15% of the time its rainy and Johnny drives 100% of the rainy days
Answer:
---->.40 (40%) drives
Conditional: .85 x .40 ---> .34
-->.85 (85%) dry weather
Conditional: .85 x .60 ---> .51
---->.60 (60%) walks
---->1.00 (100%) rains
Conditional: .15 x 1.00 --->.15
-->.15 (15%) drive
Conditional: .15 x 0 ---> 0
----> 0 others
Total - 1.00 (100%)
Homework Assign.
Ready for class Monday
Monday's Bellringer: Probability Trees
Question
1. What is the probability of choosing a green m&m?
2. What is the probability of choosing a red m&m and then a Yellow m&m?
4 colored m&m's:
8 yellow
10 red
5 blue
2 green
