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

**Solve. Show your work.**

**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?

Answer:

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?

Answer:

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?

Answer:

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?

Answer:

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?

Answer:

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.

Answer:

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.

Answer:

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.

Answer:

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.

Answer:

Factors of 24 is (1, 24), (2, 12) (3, 8) and (4, 6).

Multiples of 6 less than 20 is 6, 12, 18.

Thus they are mutually exclusive events.