1. Holt CA Course 1 11-5Probability Warm Up Warm Up California Standards California Standards Lesson Presentation Lesson PresentationPreview

2. Holt CA Course 1 11-5Probability Warm Up Write each fraction in simplest form. 1.2. 3.4. 16 20 12 36 8 64 39 195 4 5 1 3 1 8 1 5

3. Holt CA Course 1 11-5Probability Review of Grade 6 SDAP3.3 Represent probabilities as ratios, proportions, decimals between 0 and 1, and percentages between 0 and 100 and verify that the probabilities computed are reasonable; know that if P is the probability of an event, 1 – P is the probability of an event not occurring. California Standards

4. Holt CA Course 1 11-5Probability Vocabulary experiment trial outcome sample space event probability

5. Holt CA Course 1 11-5Probability An experiment is an activity in which results are observed. Each observation is called a trial, and each result is called an outcome. The sample space is the set of all possible outcomes of an experiment. Experiment Sample Space flipping a coin heads, tails rolling a number cube 1, 2, 3, 4, 5, 6

6. Holt CA Course 1 11-5Probability An event is any set of one or more outcomes. The probability of an event is a number from 0 (or 0%) to 1 (or 100%) that tells you how likely the event is to happen. You can write probability as a fraction, a decimal, or a percent. A probability of 0 means the event is impossible, or can never happen. A probability of 1 means the event is certain, or will always happen. The probabilities of all the outcomes in the sample space add up to 1.

7. Holt CA Course 1 11-5Probability 0 0.25 0.5 0.75 1 0% 25% 50% 75% 100% Never Happens about Always happens half the time happens 1 4 1 2 3 4 0 1

8. Holt CA Course 1 11-5Probability Give the probability for each outcome. Additional Example 1A: Finding Probabilities of Outcomes in a Sample Space The basketball team has a 70% chance of winning. P(win) = 70% = 0.7. P(lose) = 1 – 0.7 = 0.3, or 30%

9. Holt CA Course 1 11-5Probability Give the probability for each outcome. Additional Example 1B: Finding Probabilities of Outcomes in a Sample Space Three of the eight sections of the spinner are labeled 1, so is a reasonable estimate. P(1) = 3 8 3838

10. Holt CA Course 1 11-5Probability Additional Example 1B Continued P(2) = 3 8 Check The probabilities of all the outcomes must add to 1. 3 8 3 8 2 8 ++ = 1 Three of the eight sections of the spinner are labeled 2, so is a reasonable estimate. 3838 P(3) = 2 8 Two of the eight sections of the spinner are labeled 3, so is a reasonable estimate. 2828

11. Holt CA Course 1 11-5Probability Give the probability for each outcome. Check It Out! Example 1A The polo team has a 50% chance of winning. P(win) = 50% = 0.5. P(lose) = 1 – 0.5 = 0.5, or 50%.

12. Holt CA Course 1 11-5Probability Give the probability for each outcome. Check It Out! Example 1B Three of the eight sections of the spinner are teal, so is a reasonable estimate. P(teal) = 3 8 3838 OutcomeTealRedOrange Probability

13. Holt CA Course 1 11-5Probability Check It Out! Example 1B Continued P(red) = 3 8 Check The probabilities of all the outcomes must add to 1. 3 8 3 8 2 8 ++ = 1 P(orange) = 2 8 Three of the eight sections of the spinner are red, so is a reasonable estimate. 3838 Two of the eight sections of the spinner are orange, so is a reasonable estimate. 2828

14. Holt CA Course 1 11-5Probability To find the probability of an event, add the probabilities of all the outcomes included in the event.

15. Holt CA Course 1 11-5Probability A quiz contains 5 true-false questions. Suppose you guess randomly on every question. The table below gives the probability of each score. Additional Example 2A: Finding Probabilities of Events What is the probability of guessing 3 or more correct? The event “ three or more correct ” consists of the outcomes 3, 4, and 5. P(3 or more correct) = 0.313 + 0.156 + 0.031 = 0.5, or 50%.

16. Holt CA Course 1 11-5Probability What is the probability of guessing fewer than 2 correct? The event “ fewer than 2 correct ” consists of the outcomes 0 and 1. P(fewer than 2 correct) = 0.031 + 0.156 = 0.187, or 18.7%. Additional Example 2B: Finding Probabilities of Events A quiz contains 5 true-false questions. Suppose you guess randomly on every question. The table below gives the probability of each score.

17. Holt CA Course 1 11-5Probability A quiz contains 5 true-false questions. Suppose you guess randomly on every question. The table below gives the probability of each score. Check It Out! Example 2A What is the probability of guessing 2 or more correct? The event “ two or more correct ” consists of the outcomes 2, 3, 4, and 5. P(2 or more) = 0.313 + 0.313 + 0.156 + 0.031 = 0.813, or 81.3%.

18. Holt CA Course 1 11-5Probability What is the probability of guessing fewer than 3 correct? The event “ fewer than 3 ” consists of the outcomes 0, 1, and 2. P(fewer than 3) = 0.031 + 0.156 + 0.313 = 0.5, or 50%. Check It Out! Example 2B A quiz contains 5 true-false questions. Suppose you guess randomly on every question. The table below gives the probability of each score.

19. Holt CA Course 1 11-5Probability Lesson Quiz Use the table to find the probability of each event. 1. 1 or 2 occurring 2. 3 not occurring 3. 2, 3, or 4 occurring 0.874 0.351 0.794