1. Principles of Probability 1 “Probability is the very guide of life” -Cicero Image from csiegel3.tripod.com/csiegel3.tripod.com/

2. Principles of Probability 2 What is Probability? The likelihood of an event occurring. Scientist use probability to predict random behavior. Photo by: Ellen Isaacs www.eurekaphotos.comwww.eurekaphotos.com

3. Principles of Probability 3 Probability of an event The probability P is: P = actual outcomes total number of possible outcomes

4. Principles of Probability 4 Probabilities are between 0 and 1. Sum of probabilities is always 1. If an event probability = 1, it always happens. If an event probability = 0, it never happens.

5. Principles of Probability 5 Calculating Probability A committee has 12 students: 3 seniors 5 juniors 4 sophomores The probability a student randomly selected will be a senior is: P = 3 seniors ÷ 12 students = 0.25

6. Principles of Probability 6 Law of Large Numbers The more trials, the better the odds the relative frequency of an event gets closer to the true probability. Click on the arrow to learn more about probability Certainty from uncertainty Order from chaos.