Probability (Simple and Conditional)

Simple Probability

1

P(red)=

P(red)=1/4

2

What is the formula for simple probability? 

P(A) = (wanted outcome) / (total possible outcomes)

3

You are randomly selected in a class of 18 students to get free points on a test. 

P(YOU)=1/18

4

You and two of your closest friends are randomly selected in a class of 18 students to get free points on a test.

Must be simplified completely. 

P (You + 2 Friends) =  3/18 = 1/6 

5

Speedy Gonzales and Road Runner are in a race. What is the probability that Road Runner wins? 

P (Road Runner) =  1/2 

Conditional Probability

1

What is the probability of a 6 sided die landing on 2 given that it's an even number? 

 P(2|Even)= 

P(2|Even) = 1/3

2

What is the probability of a 6 sided die landing on 3 given that it's an odd number?

 P(3|Odd)= 

 

P (3|Odd) = 1/3

3

Using a 6 sided die ... 

 P (4 | >1)= 

P (4 | >1) = 1/5

4

P(cat|dog)=8/13

5

Using our modified deck of UNO cards P(Green | 7) =  

P(Green | 7) = 2/8 = 1/4