Warm Up Problem of the Day Lesson Presentation Lesson Quizzes

Warm Up Write each fraction in simplest form. 1. 15 21 2. 48 64 3. 9 81 4. 30 45 5 7 3 4 1 9 2 3

Problem of the Day You roll a regular pair of number cubes. How likely is it that the product of the two numbers is odd and greater than 25? Explain. Impossible; the only possible products greater than 25 (30 and 36) are even.

Sunshine State Standards MA.7.P.7.1 Determine the outcome of an experiment and predict which events are likely or unlikely.

Vocabulary experiment complement trial outcome event probability simple event compound event

An activity involving chance, such as rolling a cube, is called an experiment. Each repetition or observation of an experiment is a trial, and each result is an outcome. A set of one or more outcomes is an event. For example, rolling a 5 (one outcome) can be an event, or rolling an even number (more than one outcome) can be an event.

The probability of an event, written P(event), is the measure of how likely an event is to occur. A simple event has a single outcome. A compound event is two or more simple events. Probability is a measure between 0 and 1, as shown on the number line. You can write probability as a fraction, a decimal, or a percent.

Additional Example 1A: Determining the Likelihood of an Event Determine whether each event is impossible, unlikely, as likely as not, likely, or certain. rolling an odd number on a number cube There are 6 possible outcomes: 2, 4, 6 1, 3, 5 Not Odd Odd Half of the outcomes are odd. Rolling an odd number is as likely as not.

Additional Example 1B: Determining the Likelihood of an Event Determine whether each event is impossible, unlikely, as likely as not, likely, or certain. rolling a number less than 6 on a number cube There are 6 possible outcomes: 6 1, 2, 3, 4, 5 6 or more Less than 6 Five outcomes are less than 6. Rolling a number less than 6 is likely.

Check It Out: Example 1A Determine whether each event is impossible, unlikely, as likely as not, or certain. 1A rolling a 2 on a number cube unlikely 1B rolling a 7 on a number cube impossible

P(event) + P(complement) = 1 When a number cube is rolled, either a 5 will be rolled or it will not. Rolling a 5 and not rolling a 5 are examples of complementary events. The complement of an event is the set of all outcomes that are not the event. Because it is certain that either an event or its complement will occur when an activity is performed, the sum of the probabilities is 1. P(event) + P(complement) = 1

Additional Example 2: Using Complements A bag contains circular chips that are the same size and weight. There are 8 purple, 4 pink, 8 white, and 2 blue chips in the bag. The probability of drawing a pink chip is . What is the probability of not drawing a pink chip? 2 11 P(event) + P(complement) = 1

Additional Example 2 Continued P(event) + P(complement) = 1 P(pink) + P(not pink) = 1 + P(not pink) = 1 2 11 Substitute for P(pink). 2 11 2 11 - = - Subtract from both t sides. 2 11 P(not pink) = 9 11 Simplify The probability of not drawing a pink chip is . 9 11

Check It Out: Example 2 A bag contains 7 red marbles, 3 green marbles, and 2 yellow marbles. The probability of drawing a red or green marble is . What is the probability of drawing a yellow marble? 5 6 P (event) + P (complement) = 1 P (yellow) + P (red or green) = 1 P (yellow) + 5 6 = 1 P (yellow) = 1- = 1 6

Additional Example 3: School Application Mandy’s science teacher almost always introduces a new chapter by conducting an experiment. Mandy’s class finished a chapter on Friday. Should Mandy expect the teacher to conduct an experiment next week? Explain. Since the class will be starting a new chapter, it is likely the teacher will conduct an experiment.

Check It Out: Example 3A Bethany rarely gets home before 5 p.m. when she has band practice after school. If Bethany has band practice on Thursday, would you expect her to be home at 4 p.m. that day? Explain. If Bethany has band practice on Thursday, it’s unlikely that she would be at home at 4 P.M

Check It Out: Example 3B Terence usually buys new mp3s the day after he gets his allowance. If he got his allowance on Friday, would you expect him to buy new mp3s on Saturday? Explain. If Terence gets his allowance on Friday, it’s likely he would buy mp3s on Saturday.

Lesson Quiz for Student Response Systems Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems 18 18 18

Lesson Quiz: Part I Determine whether each event is impossible, unlikely, as likely as not, likely, or certain. 1. Bonnie’s Spanish club meets on Tuesday afternoons. How likely is it that Bonnie is at the mall on Tuesday afternoon? 2. There are 12 SUVs and 12 vans in a parking lot. How likely is it that the next vehicle to move is a van? unlikely as likely as not

Lesson Quiz: Part II Determine whether each event is impossible, unlikely, as likely as not, likely, or certain. 3. A bag holds 4 red marbles, 3 green marbles, 3 yellow marbles, and 2 blue marbles. You pull one without looking. The probability of pulling a green marble is . What is the probability of pulling a marble that is not green? 14 3 4 4. Tim never listens to his MP3 player during classes. If Tim is in math class, how likely is it that he is listening to his MP3 player? impossible

Lesson Quiz for Student Response Systems 1. Determine whether the event is impossible, unlikely, likely, or certain. rolling a 7 on a number cube A. impossible B. unlikely C. likely D. certain 21 21 21

Lesson Quiz for Student Response Systems 2. Determine whether the event is unlikely, as likely as not, likely, or certain. randomly drawing a black or white marble from a bag of black and white marbles A. impossible B. unlikely C. likely D. certain 22 22 22

Lesson Quiz for Student Response Systems 3. Erika almost always goes out with an umbrella if it is a rainy day. Today is a rainy day. How likely is it that Erika will go out with umbrella today? A. impossible B. unlikely C. likely D. certain 23 23 23