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1 Lesson 6.2.1 Probability. 2 Lesson 6.2.1 Probability California Standard: Statistics, Data Analysis, and Probability 3.3 Represent probabilities as.

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Presentation on theme: "1 Lesson 6.2.1 Probability. 2 Lesson 6.2.1 Probability California Standard: Statistics, Data Analysis, and Probability 3.3 Represent probabilities as."— Presentation transcript:

1 1 Lesson Probability

2 2 Lesson Probability California Standard: Statistics, Data Analysis, and Probability 3.3 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. What it means for you: You’ll learn about using probability as a way to describe how likely events are to happen. Key words: probability chance likely percent fraction decimal

3 3 Probability A lot of the time, you can’t say for sure whether or not one particular event will happen. But you can often say how good the chances are. Lesson Probability is a way of using numbers to describe the chance of an event happening. What are the chances that I will roll a six?

4 4 Probability Some Events Are More Likely to Happen Than Others Lesson People often talk about things that might happen, using words like “chance,” “likely,” and “probability”: “What is the probability it will snow today?” “How likely is it that the school football team will win its next game?” “What is the chance that you will go to a movie this weekend?” Impossible Very unlikely Fairly unlikely Even chance Quite likely Very likely Certain Look at the line below and think about where your answer would be for each of these questions.

5 5 Impossible Very unlikely Fairly unlikely Even chance Quite likely Very likely Certain Probability Guided Practice Solution follows… Lesson Decide where you would put the chances of the following events happening on this scale: 1.Leaves falling from the trees next fall. 2.Finding a live elephant in your bedroom when you get home. 3.Winning a raffle if you have 1 out of 100 tickets. Certain Very very unlikely Very unlikely

6 6 Impossible Very unlikely Fairly unlikely Even chance Quite likely Very likely Certain Probability Guided Practice Solution follows… Lesson Decide where you would put the chances of the following events happening on this scale: 4.Winning a raffle if you have 99 out of 100 tickets. 5.Winning a raffle if you have 1 out of 1,000,000 tickets. 6.A tossed coin landing on heads. Very likely Very very unlikely Even chance Probability

7 7 Guided Practice Solution follows… Lesson Put the events named in Exercises 1–6 in order, from most likely to least likely. 1.Leaves falling from the trees next fall. 2.Finding a live elephant in your bedroom when you get home. 3.Winning a raffle if you have 1 out of 100 tickets. 4.Winning a raffle if you have 99 out of 100 tickets. 5.Winning a raffle if you have 1 out of 1,000,000 tickets. 6.A tossed coin landing on heads. Most likelyLeast likely

8 8 Probability Probability Is a Way to Say How Likely an Event Is Lesson In math, probability is a way of describing the chance that an event will occur. Probability can be written using fractions, decimals, or percents. You can replace the words on the line below with numbers that represent how likely an event is to occur: Impossible Very unlikely Fairly unlikely Even chance Quite likely Very likely Certain 0 or 0% or 50% or 100%

9 9 Probability Lesson A probability of 0 (or 0%) means that there is no chance. A probability of 1 (or 100%) means that the event will definitely happen. 0%50%100% A probability of (or 50%) means that the event might happen, but there’s an equal chance that it won’t. 1 2

10 10 8.It will go dark tonight. 9.Your math teacher will turn into a pineapple. 10. A 6th-grader from California chosen at random will be a girl. Probability Guided Practice Solution follows… Lesson Estimate the probability that each of the following things will happen. Write your answers as percents. 100% 0% About 50%

11 Which of the probabilities above represents an impossible event? 12. Which of the probabilities above represents a certain event? Probability Guided Practice Solution follows… Lesson Use the list of probabilities below to answer Exercises 11–

12 12 Probability Probability Is Usually Calculated Exactly Lesson There are many situations where you can say exactly what the probability of an event is. This isn’t the same as saying whether an event will definitely (or not definitely) happen — it’s just a measure of how likely the event is.

13 13 Spinning the color red is certain, so the probability is 1. Probability Example 1 What is the probability of spinning the color red on this spinner? What is the probability of spinning the color blue? Solution follows… Lesson Solution Spinning the color blue is impossible, so the probability is 0.

14 14 The blue section is one-fourth of the spinner. Probability Example 2 What is the probability of spinning the color blue on this spinner? Solution follows… Lesson Solution So the probability of spinning the color blue is If you spun the spinner lots of times, about one-fourth of the spins would land on blue. = 0.25 = 25% 1 4

15 15 Probability Guided Practice Solution follows… Lesson Exercises 13–15 are about this spinner. Find the probability of spinning the colors below. Write your answers as decimals. 13. Blue 14. Yellow 15. Pink It is impossible to spin pink, so the probability is 0. Half the spinner is blue, so the probability of spinning blue is one-half or 0.5. Half the spinner is yellow, so the probability of spinning yellow is one-half or 0.5.

16 16 Probability Guided Practice Solution follows… Lesson In Exercises 16–18, find the probability of spinning the color yellow on each of the following spinners. Write your answers as fractions

17 17 Probability Independent Practice Solution follows… Lesson Each set of cards shown below is turned over and shuffled, then one card is picked. A.B. C.D. A:B:C:D:A:B:C:D: 1. a triangle card2. a star card For each set of cards, find the probability of picking:

18 18 3.How many marbles are in the bag? 4.How many marbles are red? What is the probability of drawing a red marble? 5.How many marbles are blue? What is the probability of drawing a blue marble? 6.How many marbles are yellow? What is the probability of drawing a yellow marble? Probability Independent Practice Solution follows… Lesson A bag has 1 red, 1 blue, and 2 yellow marbles in it

19 19 Probability Independent Practice Solution follows… Lesson The probability of an event occurring is. Which two values below represent this same probability? The probability of an event occurring is 55%. Which two values below represent this same probability? %0.375%37.5% 3 8 %

20 Probability Independent Practice Solution follows… Lesson In a tiled hallway, kids are jumping from one tile to the next. The probability of landing on a green tile is 60%. What fraction of the hallway area is covered with green tiles? 3 5

21 21 Probability Round Up Probability is useful because you can use it to compare the chances of different events happening. The event with the highest probability is the most likely to occur. Lesson 6.2.1


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