UNIT 5: PROBABILITY Basic Probability

Sample Space Set of all possible outcomes for a chance experiment. Example: Rolling a Die

Probability Model It is a description of some chance process that consists of two parts A sample space (S) A probability for each outcome

Tree Diagram A technique for listing the outcomes in a sample space. It contains branches showing what can happen on different trials.

Draw diagram of all possibilities of test performance on three True/False questions.

Draw the tree diagram for winning the best 2 out of 3 games.

Imagine rolling two fair, six-sided dice – one that is red and one that is green. Give a probability model for this chance process.

Event It is a subset of the sample space. It is usually designated by capital letters, like A, B, C, and so on.

Consider flipping 2 coins A = both tails B = at least one head Find P(A)P(B)

Basic Rules of Probability – (don’t write yet)

Complement

Mutually Exclusive (Disjoint) Two events are mutually exclusive (disjoint) if they have no outcomes in common and so can never occur together.

Basic Probability Rules

Find the probability: Rolling a 5 Choosing a girl in this class Drawing a king

Two marbles are pulled from a bag holding one red, one white, one blue, and two green marbles. A={the blue marble is drawn} B={a green marble is drawn}

Distance learning courses are rapidly gaining popularity among college students. Randomly select an undergraduate student who is taking a distance-learning course for credit, and record the student’s age. Here is the probability model. Show that this is a legitimate probability model. Find the probability that the chosen student is not in the traditional college age group (18 to 23). Age Group (Yr):18 to 2324 to 2930 to 3940 or over Probability:

Choose an American adult at random. Define two events: A = the person has a cholesterol level of 240 mg per deciliter of blood (mg/dl) or above (high cholesterol). B = the person has a cholesterol level of 200 to 239 mg/dl (bordering high cholesterol) According to the American Heart Association, P(A) = 0.16 and the P(B) = Explain why events A and B are mutually exclusive. What is P(A and B)? What is P(A or B)? If C is the event that ther person chosen has normal cholesterol (below 200 mg/dl), what is P(C)?

Homework