Holt CA Course Probability Warm Up Warm Up California Standards California Standards Lesson Presentation Lesson PresentationPreview

Holt CA Course Probability Warm Up Write each fraction in simplest form

Holt CA Course Probability 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

Holt CA Course Probability Vocabulary experiment trial outcome sample space event probability

Holt CA Course Probability 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

Holt CA Course Probability 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.

Holt CA Course Probability % 25% 50% 75% 100% Never Happens about Always happens half the time happens

Holt CA Course Probability 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%

Holt CA Course Probability 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) =

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

Holt CA Course Probability 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%.

Holt CA Course Probability 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) = OutcomeTealRedOrange Probability

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

Holt CA Course Probability To find the probability of an event, add the probabilities of all the outcomes included in the event.

Holt CA Course Probability 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) = = 0.5, or 50%.

Holt CA Course Probability 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) = = 0.187, 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.

Holt CA Course Probability 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) = = 0.813, or 81.3%.

Holt CA Course Probability 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) = = 0.5, 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.

Holt CA Course Probability Lesson Quiz Use the table to find the probability of each event or 2 occurring 2. 3 not occurring 3. 2, 3, or 4 occurring