AP Statistics / Unit 2: Probability, Random Variables, and Probability Distributions
2.4 Introduction to Probability
Notes
- Probabilities are between 0 and 1; all outcomes sum to 1.
- For equally likely outcomes: $\displaystyle P(A)=\frac{\text{outcomes in }A}{\text{total outcomes}}$.
- Complement: $P(A^c)=1-P(A)$.
Practice
Rolling a fair die, $P(\text{even})=$
3 of 6 outcomes.
$P(\text{rain})=0.35$. $P(\text{no rain})=$
Complement.
Which can't be a probability?
Probabilities are at most 1.
Ready for more? Take the Unit 2 test.