This handy Math in Focus Grade 8 Workbook Answer Key Chapter 11 Probability detailed solutions for the textbook questions.

## Math in Focus Grade 8 Course 3 B Chapter 11 Answer Key Probability

### Math in Focus Grade 8 Chapter 11 Quick Check Answer Key

A box has 2 black balls, 7 red balls, and 3 green balls. A ball is randomly chosen from the box.

Question 1.
What is the probability of choosing a green ball?
Given,
A box has 2 black balls, 7 red balls, and 3 green balls.
Total number of balls = 2 + 7 + 3 = 12
We have to find the probability of choosing a green ball.
Number of green balls = 3
Probability of choosing green balls = 3/12 = 1/4
Thus the Probability of choosing green balls is 1/4.

Question 2.
What is the probability of choosing a black ball?
Given,
A box has 2 black balls, 7 red balls, and 3 green balls.
Total number of balls = 2 + 7 + 3 = 12
We have to find the probability of choosing a black ball.
Number of green balls = 2
Probability of choosing green balls = 2/12 = 1/6
Thus the Probability of choosing green balls is 1/6.

Question 3.
What is the probability of choosing a blue ball?
Given,
A box has 2 black balls, 7 red balls, and 3 green balls.
Total number of balls = 2 + 7 + 3 = 12
We have to find the probability of choosing a black ball.
Number of blue balls = 0
Thus the Probability of choosing blue balls is 0.

Question 4.
What is the probability of choosing a ball that is not red?
A box has 2 black balls, 7 red balls, and 3 green balls.
Total number of balls = 2 + 7 + 3 = 12
We have to find the probability of choosing a ball that is not red.
Number of red balls = 7
The number of balls that are not red is 5
So, the probability of choosing a ball that is not red is 5/12.

Question 5.
What is the probability of choosing a red or green ball?
Given that,
A box has 2 black balls, 7 red balls, and 3 green balls.
Total number of balls = 2 + 7 + 3 = 12
Find the probability of choosing a red or green ball.
Number of green balls = 2
Probability of choosing green balls = 2/12 = 1/6
Thus the Probability of choosing green balls is 1/6.
Number of red balls = 7
Probability of choosing green balls = 7/12
The probability of choosing a red or green ball is 9/12 = 3/4.

Tell whether the events X and Y are mutually exclusive events.

Question 6.
A fair coin and a fair six-sided number die are tossed. X is the event that a head is obtained. Y is the event that a six is obtained.
Given,
A fair coin and a fair six-sided number die are tossed.
X is the event that a head is obtained.
The probability of getting heads is p(A) = 1
Y is the event that a six is obtained.
The probability of getting six is p(B) = 1
Yes the events X and Y are not mutually exclusive events.

Question 7.
A fair six-sided number die is rolled. X is the event of obtaining a three. Y is the event of obtaining a five.
A fair six-sided number die is rolled.
X is the event of obtaining a three.
Y is the event of obtaining a five.
Events 3 and 5 are mutually exclusive because we cannot get 3 and 5 at the same time.

Question 8.
Two fair six-sided number dice are tossed. X is the event that the sum of the score is six. Y is the event that the sum of the score is 10.
Given,
Two fair six-sided number dice are tossed.
X is the event that the sum of the score is six.
Y is the event that the sum of the score is 10.
Total number of possible results from two six-sided dice is 6 × 6 = 36.
The possibility of the sum of the score is six is (1, 5) (2, 4) (3, 3) (4, 1) (5, 1) = 5/36
The sum of the score is 10 is (4, 6) (5, 5) (6, 4) = 3/36 = 1/12
Thus they are mutually exclusive events.

Question 9.
X is the event consisting of the factors of 24. Y is the event consisting of multiples of 6 less than 20.