August 16 2010 Simple Probability Warmup Suppose most

August 16, 2010 Simple Probability

Warm-up Suppose most of your clothes are dirty and you are left with 3 pants and 8 shirts. How many choices do you have or how many different ways can you dress? You go to a restaurant to get some breakfast. The menu says pancakes, crepes, & waffles; for the sides, you can choose from eggs, bacon, and sausage; and to drink, they serve coffee, juice, hot chocolate, and tea. How many different ways can you order breakfast choosing one from each category?

Warm-up Suppose most of your clothes are dirty and you are left with 3 pants and 8 shirts. How many choices do you have or how many different ways can you dress? 3 x 8 = 24 You go to a restaurant to get some breakfast. The menu says pancakes, crepes, & waffles; for the sides, you can choose from eggs, bacon, and sausage; and to drink, they serve coffee, juice, hot chocolate, and tea. How many different ways can you order breakfast choosing one from each category?

Warm-up Suppose most of your clothes are dirty and you are left with 3 pants and 8 shirts. How many choices do you have or how many different ways can you dress? 3 x 8 = 24 You go a restaurant to get some breakfast. The menu says pancakes, crepes, & waffles; for the sides, you can choose from eggs, bacon, and sausage; and to drink, they serve coffee, juice, hot chocolate, and tea. How many different ways can you order breakfast choosing one from each category? 3 x 4 = 36

Simple Probability

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Simple Probability

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? Simple Probability

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? 4/36 = 1/9 Simple Probability

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? 4/36 = 1/9 Simple Probability Example 2: What is the probability of drawing a king from a deck of cards?

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? 4/36 = 1/9 Simple Probability Example 2: What is the probability of drawing a king from a deck of cards? 4/52 or 1/13

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? 4/36 = 1/9 Simple Probability Example 2: What is the probability of drawing a king from a deck of cards? 4/52 or 1/13 Example 3: What is the probability of drawing a queen of hearts from a deck of cards?

probability of an event or P(event) is number of favorable outcomes total number of possible outcomes Example 1: Sarah rolls two 6 -sided numbered cubes. What is the probability that the two numbers added together will equal 5? 4/36 = 1/9 Simple Probability Example 2: What is the probability of drawing a king from a deck of cards? 4/52 or 1/13 Example 3: What is the probability of drawing a queen of hearts from a deck of cards? 1/52

“OR” • P(A or B) = P(A) + P(B) Example: When you flip a fair coin and roll a number cube, what is the P(head or 4)? P(head or 4) = ½ + 1/6 = 3/6 + 1/6 = 4/6 = 2/3

• Example: Alfred is going to the Lakeshore Animal Shelter to pick a new pet. Today, the shelter has 8 dogs, 7 cats, and 5 rabbits available for adoption. If Alfred randomly picks an animal to adopt, what is the probability that the animal would be a cat or a dog? 8/20 + 7/20 = 15/20 = 3/4

“And” • P(A and B) = P(A) x P(B) • Example: When you flip a fair coin and roll a number cube, what is the P(head and 4)? • P(head, 4) = ½ x 1/6 = 1/12

Practice 1. P(heads, hearts) = 13/104 2. P(tails, four) = 4/104

Practice 1. P(roll even #, spin odd) = 2. P(roll a 2, spin a 7) = 3. P(roll a 7, spin an even #) = 1/48 0