EGR Sample Space, S The set of all possible outcomes of an experiment. Each outcome is an element or member or sample point. If the set is finite (e.g., H/T on coin toss, number on the die, etc.): –S = {H, T} –S = {1, 2, 3, 4, 5, 6} –in general, S = {e 1, e 2, e 3, …, e n } where e i = the outcomes of interest Note: sometimes a tree diagram is helpful in determining the sample space…

EGR Sample Space Example: The sample space of gender and specialization of all BSE students in the School of Engineering is …

EGR Events A subset of the sample space reflecting the specific occurrences of interest. Example, –All female students, F =

EGR Events Complement of an event, (A’, if A is the event) –e.g., students who are not female, Intersection of two events, (A ∩ B) –e.g., engineering students who are EVE and female, Mutually exclusive or disjoint events Union of two events, (A U B)

EGR Venn Diagrams Example, events V (EVE students) and F (female students)

EGR Other Venn Diagram Examples Mutually exclusive events Subsets

EGR Example: Students who are male, students who are ECE, students who are on the ME track in ECE, and female students who are required to take ISE 412 to graduate.

EGR Sample Points Multiplication Rule –If event A can occur n 1 ways and event B can occur n 2 ways, then an event C that includes both A and B can occur n 1 n 2 ways. –Example, if there are 6 ways to choose a female engineering student at random and there are 6 ways to choose a male student at random, then there are 6 * 6 = 36 ways to choose a female and a male engineering student at random.

EGR Another Example Example 2.14, pg. 41

EGR Permutations definition: an arrangement of all or part of a set of objects. The total number of permutations of the 6 engineering specializations in MUSE is … In general, the number of permutations of n objects is n!

EGR Permutations Let’s say we want to know how many smaller arrangements of the set we can make, e.g. –If we take the number of specializations 3 at a time (n = 6, r = 3), the number of permutations is In general,

EGR Example A new group, the MUSE Ambassadors, is being formed and will consist of two students (1 male and 1 female) from each of the BSE specializations. If a prospective student comes to campus, he or she will be assigned one Ambassador at random as a guide. If three prospective students are coming to campus on one day, how many possible selections of Ambassador are there?

EGR Looking at a more complicated example … example 2.18, pg. 44

EGR Combinations Selections of subsets without regard to order. Example: How many ways can we select 3 guides from the 12 Ambassadors?

EGR Probability The probability of an event, A is the likelihood of that event given the entire sample space of possible events. 0 ≤ P(A) ≤ 1 P(ø) = 0 P(S) = 1 For mutually exclusive events, P(A 1 U A 2 U … U A k ) = P(A 1 ) + P(A 2 ) + … P(A k )

EGR Calculating Probabilities Examples: 1.There are 26 students enrolled in this section of EGR 252, 3 of whom are BME students. The probability of selecting a BME student at random off of the class roll is: P = ______________________ 2.The probability of being dealt 2 aces & 3 jacks in a 5- card poker hand is:

EGR Additive Rule Examples 1.Draw 1 Card. Note Kind, Color & Suit. –Probabilities associated with drawing an ace and with drawing a black card are shown in the following contingency table: –Therefore the probability of drawing an ace or a black card is given by: Type Color Total RedBlack Ace224 Non-Ace24 48 Total26 52

EGR Additive Rules 2.After the first card is drawn, it is returned to the deck which is shuffled. Another card is drawn. What is the probability that at least one of the cards is an ace?

EGR Applications of Probability Example: An appliance manufacturer has learned of an increased incidence of short circuits and fires in a line of ranges sold over a 5 month period. A review of the FMEA data indicates the probabilities that if a short circuit occurs, it will be at any one of several locations is as follows: LocationP House Junction0.46 Oven/MW junction0.14 Thermostat0.09 Oven coil0.24 Electronic controls0.07

EGR Applications of Probability The probability that the short circuit does not occur at the house junction is … The probability that the short circuit occurs at either the Oven/MW junction or the oven coil is … The probability that both the electronic controls and the thermostat short circuit simultaneously is …

EGR Your turn … Problem 3, page 46