Probability

NOTE 1: Definitions Probability is a measure of how likely it is that an event will happen. It can be expressed as a fraction or a decimal point and is on a continuum between 0 and 1. 0 ¼ ½ ¾ 1 Impossible unlikely may or may likely will definitely not occur occur

An experiment is a process with a result that depends on chance. Example: Picking a card from a pack of 52 A trial is one perfomance of an experiment. Example: Picking a card once An outcome is the result of a trial. Example: Getting the 9 of Hearts The sample space (S) is the set of all possible outcomes of an experiment. Example: S = {Ace H, King H, … A Spades} An event (E) is a subset of the sample space. Example: E = Getting a Club

Experimental Probability The results of experiments allow us to determine relative probabilities from patterns in the past. P(event) = the number of times the event occurs total number of trials

Examples: Find the probability that a student in the IB class has blue eyes. P(Blue eyes) = The probability an event will not occur = 1 – P (event) Find the probability that a student in the IB class does NOT have blue eyes. P(Not Blue eyes) = 1 – P(Blue eyes)

Standard Level: Page 471 Exercise 19A Studies: Page 492 Exercise 16A.1 – A.2