1. How likely it is that some events will occur?
1: Chance Experiments
How likely it is that some events will occur?
Suppose you and your friend will play a game using the spinner shown here:
Decide who will go first.
Each person picks a color. Both players cannot pick the same color.
Each person takes a turn spinning the spinner and recording what color the spinner stops on. The winner is the person whose color is the first to happen 𝟏𝟎 times.
Play the game and remember to record the color the spinner stops on for each spin.
Player 1
Player 2
Dr. Basta Grade 7, Module 5, Lessons 1 -

2. Dr. Basta Grade 7, Module 5, Lessons 1 -
How fair is this game?
Who do you think will win the game?
The person selecting green has an advantage.
Will it make a difference who goes first?
The game is designed so that the spinner landing on green is more likely to occur. Therefore, if the first person selects green, this person has an advantage.
Do you think this game is fair?
No. The spinner is designed so that green will occur more often. As a result, the student who selects green will have an advantage.
Dr. Basta Grade 7, Module 5, Lessons 1 -

3. What are the chances green will win?
Which spinner gives green the best chances to win?
Spinner B, because the green section is larger for this spinner than for the other spinners.
Dr. Basta Grade 7, Module 5, Lessons 1 -

4. What is Probability?
A probability is represented by a number between 𝟎 and 𝟏.
It can be expressed in several ways:
a fraction (don’t simplify),
a decimal,
or a percent.
Dr. Basta Grade 7, Module 5, Lessons 1 -

5. What are my chances?
Some events are impossible. These events have a probability of 0.
You have a bag with two green cubes, and you select one at random.
What is the chance of selecting a blue cube?
There is no way to select a blue cube if there are no blue cubes in the bag.
Fraction
Decimal
Percentage
0 2
0.0 0%
Dr. Basta Grade 7, Module 5, Lessons 1 -

6. What are my chances?
Some events are certain. These events have a probability of 𝟏.
You have a bag with two green cubes, and you select one at random.
What are the chances of selecting a green cube?
You will always get a green cube if there are only green cubes in the bag.
Fraction
Decimal
Percentage
2 2
1.0
100%
Dr. Basta Grade 7, Module 5, Lessons 1 -

7. What are my chances?
Some events are classified as equally likely to happen or to not happen. These events have a probability of 𝟏 𝟐 .
You have a bag with one blue cube and one red cube and you randomly pick one.
What are the chances of selecting a blue cube?
You will select a blue cube one-half of the time.
Fraction
Decimal
Percentage
1 2
0.5
50%
Dr. Basta Grade 7, Module 5, Lessons 1 -

8. Dr. Basta Grade 7, Module 5, Lessons 1 -
What are my chances?
Some events are less likely to happen than to not happen. These events will have a probability that is less than 𝟎.𝟓. These events could be described as “unlikely” to occur.
If you have a bag that contains eight blue cubes and two red cubes, and you select one at random, it is unlikely that you will get a red cube.
Even though it is not impossible to get a red cube, a red cube would not be selected very often because there are many more blue cubes than red cubes.
Fraction
Decimal
Percentage
0 < P(R)< 1 2
0< P(R)<0.5
0<P(R)<50%
Dr. Basta Grade 7, Module 5, Lessons 1 -

9. Dr. Basta Grade 7, Module 5, Lessons 1 -
What are my chances?
Some events are more likely to happen than to not happen. These events will have a probability that is greater than 𝟎.𝟓. These events could be described as “likely” to occur.
If you have a bag that contains eight blue cubes and two red cubes, and you select one at random, it is likely that you will get a blue cube.
Even though it is not certain that you will get a blue cube, a blue cube would be selected most of the time because there are many more blue cubes than red cubes.
Fraction
Decimal
Percentage
1 2 < P(B) < 2 2
0.5 < P(B) < 1
50% < P(B) < 100%
Dr. Basta Grade 7, Module 5, Lessons 1 -

10. Dr. Basta Grade 7, Module 5, Lessons 1 -
Practice
1. Match each spinner below with the words Impossible, Unlikely, Equally likely to occur or not occur, Likely and Certain to describe the chance of the spinner landing on black.
Dr. Basta Grade 7, Module 5, Lessons 1 -

11. Dr. Basta Grade 7, Module 5, Lessons 1 -
Practice
2. Decide if each of the following events is Impossible, Unlikely, Equally likely to occur or not occur, Likely, or Certain to occur.
A vowel will be picked when a letter is randomly selected from the word “lieu.”
A vowel will be picked when a letter is randomly selected from the word “math.”
A blue cube will be drawn from a bag containing only five blue and five black cubes.
A red cube will be drawn from a bag of 100 red cubes.
A red cube will be drawn from a bag of 10 red and 90 blue cubes.
Dr. Basta Grade 7, Module 5, Lessons 1 -

12. Dr. Basta Grade 7, Module 5, Lessons 1 -
Practice
3. A shape will be randomly drawn from below. Decide where each event would be located on the probability scale. Then, place the letter for each event on the appropriate place on the probability scale.
Event:
A circle is drawn.
A square is drawn.
A star is drawn.
A shape that is not a square is drawn
Dr. Basta Grade 7, Module 5, Lessons 1 -

13. Dr. Basta Grade 7, Module 5, Lessons 1 -
Practice
4. Write a letter in each of the cubes below so that it would be equally likely to choose a blue or yellow cube.
5. Write a letter in each of the cubes below so that it would be likely but not certain to choose a blue cube from the bag.
Dr. Basta Grade 7, Module 5, Lessons 1 -

14. Dr. Basta Grade 7, Module 5, Lessons 1 -
Practice
6. Write a letter in each of the cubes below so that it would be unlikely but not impossible to choose a blue cube from the bag.
7. Write a letter in each of the cubes below so that it would be impossible to choose a blue cube from the bag.
Dr. Basta Grade 7, Module 5, Lessons 1 -

15. Dr. Basta Grade 7, Module 5, Lessons 1 -
1. A Unlikely; B Likely; C Impossible; D. Equally Likely; E. Certain
2A. Likely; most of the letters of the word lieu are vowels.
2B. Unlikely; most of the letters of the word math are not vowels.
3C. Equally likely to occur or not occur; the number of blue and black cubes in the bag is the same.
4D. Certain; the only cubes in the bag are red.
5E. Unlikely; most of the cubes in the bag are blue.
3A. Impossible; B. Equally Likely; C. Unlikely; D. Equally Unlikely
4. Color 𝟓 five blue and 𝟓 five yellow.
5. 𝟕, 𝟖, or 𝟗 blue, and the rest any other color.
6. 𝟏, 𝟐, or 𝟑 blue, and the others any other color.
7. Any color but blue.
Dr. Basta Grade 7, Module 5, Lessons 1 -

16. Dr. Basta Grade 7, Module 5, Lessons 1 -
Lesson Summary
Probability is a measure of how likely it is that an event will happen.
A probability is a number between 𝟎 and 𝟏.
The probability scale is:
Dr. Basta Grade 7, Module 5, Lessons 1 -