11-1 Introduction to Probability

Course 1

Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

Warm UpWrite each fraction as a decimal and as a percent.

1.

2.

3.

4.

0.75; 75%

0.50; 50%

Course 1

11-1 Introduction to Probability

12__

34__

29__

38__ 0.375; 37.5%

0.2; 22.2%__

Problem of the Day

What fraction of the numbers from 0 to 99 are divisible by 3?.

or 34100

___ 17 50

__

Course 1

11-1 Introduction to Probability

Learn to estimate the likelihood of an event and to write and compare probabilities.

Course 1

11-1 Introduction to Probability

Vocabulary

probability

Insert Lesson Title Here

Course 1

11-1 Introduction to Probability

Probability is the measure of how likely an event is to occur.

Course 1

11-1 Introduction to Probability

Probabilities are written as fractions or decimals from 0 to 1 or as percents from 0% to 100%. The higher an event’s probability, the more likely that event is to happen.

• Events with a probability of 0, or 0%, never happen.

• Events with a probability of 1, or 100%, always happen.

• Events with a probability of 0.5, or 50%, have the same chance of happening as of not happening.

Course 1

11-1 Introduction to Probability

Impossible Unlikely As likely as not Likely Certain

0 0.5 1

21__ 0% 100%

50%

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11-1 Introduction to Probability

Insert Lesson Title HereAdditional Example 1A & 1B: Estimating the

Likelihood of an Event

Write impossible, unlikely, as likely as not, likely, or certain to describe each event.

A. You will roll an even number on a standard number cube.

B. The month of February has 28 days.

as likely as not

certain

A standard number cube is numbered from 1 to 6.

Helpful Hint

Course 1

11-1 Introduction to Probability

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Additional Example 1C & 1D: Estimating the Likelihood of an Event

Write impossible, unlikely, as likely as not, likely, or certain to describe each event.

C. This spinner lands on blue.

D. This spinner lands on an odd number.

unlikely

impossible

Course 1

11-1 Introduction to Probability

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Try This: Example 1A & 1B

Write impossible, unlikely, as likely as not, likely, or certain to describe each event.

A. You guess a number between 1 and 1000.

B. You will roll an odd number on a standard number cube.

unlikely

as likely as not

A standard number cube is numbered from 1 to 6.

Helpful Hint

Course 1

11-1 Introduction to Probability

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Try This: Example 1C & 1D

Write impossible, unlikely, as likely as not, likely, or certain to describe each event.

C. This spinner lands on green.

D. This spinner lands on an even number.

unlikely

certain

Course 1

11-1 Introduction to Probability

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Additional Example 2A & 2B: Writing Probabilities

A. The weather report gives a 75% chance of snow. Write this probability as a decimal and as a fraction.

75% = 0.75

B. The chance of being chosen is 0.8. Write this probability as a fraction and as a percent.

Write as a decimal.

75% = = 75

100___ 3

4__ Write as a fraction in

simplest form.

0.8 = = 8

10__ 4

5__ Write as a fraction in

simplest form.

0.8 = 80% Write as a percent.

Course 1

11-1 Introduction to Probability

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Additional Example 2C: Writing Probabilities

C. There is a chance of getting a ring. Write

this probability as a decimal and as a percent.

Write as a decimal.

Write as a percent.

750__

= 7 ÷ 50 = 0.147

50__

= = = 14% 7 • 2

50 • 2_____7

50__ 14

100___

In Example 2C, after you find the decimal form

of , you can use it to find the percent.

0.14 = 14%.

Helpful Hint

750__

Course 1

11-1 Introduction to Probability

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Try This: Example 2A & 2B

A. The weather report gives a 25% chance of snow. Write this probability as a decimal and as a fraction.

25% = 0.25

B. The chance of being chosen is 0.6. Write this probability as a fraction and as a percent.

Write as a decimal.

25% = = 25

100___ 1

4__ Write as a fraction in

simplest form.

0.6 = = 6

10__ 3

5__ Write as a fraction in

simplest form.

0.6 = 60% Write as a percent.

Course 1

11-1 Introduction to Probability

Insert Lesson Title Here

Try This: Example 2C

C. There is a chance of getting a ring. Write

this probability as a decimal and as a percent.

Write as a decimal.

Write as a percent.

425__

= 4 ÷ 25 = 0.164

25__

= = = 16% 4 • 4

25 • 4_____4

25__ 16

100___

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11-1 Introduction to Probability

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Additional Example 3A: Comparing Probabilities

A. On a standard number cube, there is a 50%

chance of rolling a multiple of 2 and a 33 %

chance of rolling a multiple of 3. Is it more likely to roll a multiple of 2 or a multiple of 3?

It is more likely to roll a multiple of 2.

Compare: 33 % < 50%13__

13__

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11-1 Introduction to Probability

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Additional Example 3B: Comparing Probabilities

B. When you spin a certain spinner, there is a 15% chance that it will land on yellow, a 15% chance it will land on green, and a 70% chance that it will land on purple. Is it more likely to land on purple or on green?

It is more likely to land on purple than on green.

Compare: 70% > 15%

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11-1 Introduction to Probability

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Try This: Example 3A

A. When you spin a certain spinner, there is a 25% chance that it will land on purple, a 35% chance it will land on green, and a 40% chance that it will land on red. Is it more likely to land on red or on green?

It is more likely to land on red than on green.

Compare: 40% > 35%

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11-1 Introduction to Probability

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Try This: Example 3B

B. When you spin a certain spinner, there is a

9% chance that it will land on yellow, a 35 %

chance it will land on brown, and a 55 %

chance that it will land on blue. Is it more likely to land on brown or on yellow?

It is more likely to land on brown than on yellow.

Compare: 9% < 35 %13__

13__

23__

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11-1 Introduction to Probability

Lesson QuizWrite impossible, unlikely, equally likely, likely, or certain to describe each event.

1. The sun will rise tomorrow.

2. You will roll 13 when rolling two dice.

3. There is a 0.125 chance of picking the winning ticket. Write this probability as a fraction and as a percent.

4. At Hamburger Hut, there is a 20% chance of getting a plastic dinosaur cup and a 35% chance of getting a plastic rabbit cup. It is less likely that you will receive a rabbit cup or dinosaur cup?

impossible

certain

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dinosaur cup

, 12.5%1

8__

Course 1

11-1 Introduction to Probability