1. Probability Probability is the measure of how likely an event is. An event is one or more outcomes of an experiment. An outcome is the result of a single trial of an experiment.

2. What is the Probability of Drawing a club from a deck of cards? Events = 13 Outcomes = 52 Probability = 13/52 or ¼ or.25 or 25%

3. The Special Addition Rule If event A and event B are mutually exclusive, then More generally, if events A, B, C, … are mutually exclusive, then That is, for mutually exclusive events, the probability that at least one of the events occurs is equal to the sum of the individual probabilities.

4. In a group of 101 students 30 are freshmen and 41 are sophomores. Find the probability that a student picked from this group at random is either a freshman or sophomore. This makes sense since 71 of the 101 students are freshmen or sophomores Note that P(freshman) = 30/101 and P(sophomore) = 41/101. P(freshman or sophomore) = 30/101 + 41/101 71/101

5. The Special Multiplication Rule (for independent events) If events A, B, C,... are independent, then P(A & B & C &  ) = P(A)  P(B)  P(C)   What is the probability of all of these events occurring: 1.Flip a coin and get a head 2.Draw a card and get an ace 3.Throw a die and get a 1 P(A & B & C ) = P(A) · P(B) · P(C) = 1/2 X 1/13 X 1/6

6. Deviation Difference between the expected and the observed Difference between the expected and observed divided by the expected results time 100 to convert it to a percent Deviation = (50-45) / 50 Deviation = 10 % or.10 100 coin tosses 45 heads 55 tails

7. As trials go up, deviation goes down 3 rd Rule of Probability for Biology Observed results get closer to expected results.

8. If a condom is 95 percent effective at preventing pregnancy, how many babies would you expect from 1 million condoms manufactured and used? 5 per 100 or 50,000 babies expected.