G8. CLS Book 9. Chapter 12. Probability

Chapter 12.
Probability

​G8. CLS
Coursebook 9

Getting Started

By Fatmawati Fatmawati

What is probability?

• Probability is how likely something will occur.

• Think of probability of the chance something can or cannot happen.

Remember:

• Probability is the chance something will happen on a scale from 0 to 1.

  
  

  
  

• 
  

How to read the probability scale:

• Impossible (0%): something cannot occur

• Unlikely: there is a small percentage of occurring

• Even Chance (50%): there is a 50% chance it can occur and 50% it cannot

• Likely: there more of a chance something occurring than not

• Certain (100%): it will happen

Theoretical vs Experimental Probability

​Click on the video.

Multiple Choice

The probability it will rain tomorrow is 0.15

Work out the probability it will not rain tomorrow.

• 0.50
• 0.85
• 0.25
• 0.70

Multiple Choice

A coin is flipped and a dice is rolled.

Work out the probability of

head and 6

• 1/6
• 1/8
• 1/4
• 1/12

Multiple Choice

A coin is flipped and a dice is rolled.

Work out the probability of

tail and an odd number.

• 1/2
• 1/6
• 3/4
• 1/4

Multiple Choice

A spinner has 5 different coloured sectors. In 50 spins it lands on red 13 times.

Work out the experimental probability of landing on red.

• $$\frac{13}{50}$$

• $$\frac{2}{25}$$

• $$\frac{1}{5}$$

• $$\frac{1}{10}$$

Multiple Choice

A spinner has 5 different coloured sectors. In 50 spins it lands on red 13 times.

Work out the theoretical probability of landing on red.

• $$\frac{13}{50}$$

• $$\frac{2}{25}$$

• $$\frac{1}{5}$$

• $$\frac{1}{10}$$

Multiple Choice

The probability a football team will win its next match is 60%.

The probability it will draw is 15%.

Work out the probability it will lose.

• 25%
• 20%
• 40%
• 30%

Math Response

You roll a fair dice.

Work out the probability of rolling

a 3

Type answer here

Correct Answer: \frac{1}{6}

Deg^°

Rad

Math Response

You roll a fair dice.

Work out the probability of rolling

an even number.

Type answer here

Correct Answer: \frac{1}{2}

Deg^°

Rad

Math Response

You roll a fair dice.

Work out the probability of rolling

a 3 or an even number.

Type answer here

Correct Answer: \frac{2}{3}

Deg^°

Rad

Math Response

A bag contains a large number of coloured balls. The balls are yellow,

green, brown, blue and pink.

P(yellow) = 0.1 P(green) = 0.25 P(brown) = 0.35 P(blue) = 0.05

A ball is taken out of the bag at random.

Work out the probability that the ball is green or blue

Type answer here

Correct Answer: 0.3

Deg^°

Rad

Math Response

A bag contains a large number of coloured balls. The balls are yellow,

green, brown, blue and pink.

P(yellow) = 0.1 P(green) = 0.25 P(brown) = 0.35 P(blue) = 0.05

A ball is taken out of the bag at random.

Work out the probability that the ball is brown or yellow

Type answer here

Correct Answer: 0.45

Deg^°

Rad

Math Response

A bag contains a large number of coloured balls. The balls are yellow,

green, brown, blue and pink.

P(yellow) = 0.1 P(green) = 0.25 P(brown) = 0.35 P(blue) = 0.05

A ball is taken out of the bag at random.

Work out the probability that the ball is pink

Type answer here

Correct Answer: 0.

Deg^°

Rad

Multiple Choice

You roll 2 dice and find the total. The probability of a total of 2 is 0.028. The probability of a total of 3 is 0.056. Work out the probability that the total is a 2 or 3

• 0.084
• 0.050
• 0.100
• 0.072

Multiple Choice

You roll 2 dice and find the total. The probability of a total of 2 is 0.028. The probability of a total of 3 is 0.056. Work out the probability that the total is more than 3

• 0.500
• 0.750
• 0.840
• 0.916

Dropdown

The temperature each day at midday can be low, average, high or very high. The forecast for Monday is P(low) = 0.15 P(average) = 0.55 P(high) = 0.25. Work out the probability that the temperature on Monday is :

a). not low : ​

Select answer

b). low or average :​

Select answer

c). very high.​

Select answer

Drag and Drop

There are 50 people in a room. There are 7 girls, 13 boys and 19 women. The rest of the people are men. One person is chosen at random. Work out the probability that the person is

a). a child :​

Placeholder

b). a female:​

Placeholder

c). an adult:​

Placeholder

d). a male:​

Placeholder

Drag these tiles and drop them in the correct blank above

answer option

0.4

0.52

0.6

0.48

Multiple Choice

Which of the following are examples of mutually exclusive events?

• Drawing a card: getting a queen or a heart.

• Rolling a die: getting a number less than 4 or an odd number.

• Drawing a card: getting a face card or a diamond.

• Rolling a die: getting a 3 or a 6.

Multiple Choice

Which of the following are examples of independent events?

• Drawing a card from a deck, not replacing it, then drawing another.

• Rolling a die twice.

• Selecting a student from a class, then selecting another without replacing the first.

• Picking a sock from a drawer, not putting it back, then picking another.

Multiple Choice

Which of the following are examples of dependent events?

• Flipping a coin and rolling a die.

• Drawing two cards with replacement.

• Drawing two marbles without replacement.

• Tossing a coin twice.

Multiple Choice

Consider the following events:

1. rolling a fair six-sided die twice.

2. Flipping a fair coin twice.

3. Drawing a red card from a standard deck card , not replacing it, and then draw another card.

4. Selecting a student from a class, recording their hair colour, and then selecting another student from the same class excluding the first one.

Which of the above option are valid example of independent events?

• 2 and 4
• 1 and 3
• 1 and 2
• 3 and 4

Multiple Select

Which of the following are examples of mutually exclusive events?

• Rolling a die: getting a 2 or a 5.

• Drawing a card: getting a red card or a black card.

• Rolling a die: getting an even number or a multiple of 3.

• Drawing a card from a deck of card: getting a king or a heart.

• Selecting a person: male or female.

Multiple Choice

Zara rolls a dice 50 times. Here are the result.

What is the relative frequency of Zara getting more than 4.

• 0.1
• 0.2
• 0.3
• 0.4

Multiple Choice

A spinner has five equal sectors coloured red, green, black, yellow and white.

The spinner is spun 20 times. It lands on black 4 times.

Work out the relative frequency of black.

• 0.2
• 0.15
• 0.1
• 0.25

Multiple Choice

A spinner has five equal sectors coloured red, green, black, yellow and white.

The spinner is spun 20 times. It lands on black 4 times.

The spinner is spun another 30 times. It lands on black another 7 times.

Work out the relative frequency of black for all 50 spins.

• 0.10
• 0.30
• 0.15
• 0.22

Multiple Choice

A group of people were asked to name their favorite meal (as shown on the table). If the relative frequency of snack is 0.2, How many people choose snack as their favorite snack?

• 12
• 10
• 8
• 5

Multiple Choice

Adira took two marbles from a bag containing three yellow marbles and two blue marbles. Find the probability that the marbles were different.

• $$\frac{15}{25}$$

• $$\frac{12}{25}$$

• $$\frac{4}{25}$$

• $$\frac{10}{25}$$

Multiple Choice

An unbiased coin is flipped twice.

Find the probability of getting a head and then a tail?

• $$\frac{1}{4}$$

• $$\frac{1}{2}$$

• $$\frac{3}{4}$$

• $$\frac{4}{5}$$

Multiple Choice

Consider the following events:

1. rolling a fair six-sided die twice.

2. Flipping a fair coin twice.

3. Drawing a red card from a standard deck card , not replacing it, and then draw another card.

4. Selecting a student from a class, recording their hair colour, and then selecting another student from the same class excluding the first one.

   Which of the above option are valid example of independent events?

• 2 and 4
• 1 and 3
• 1 and 2
• 3 and 4

Multiple Choice

Mikel has five red, seven brown, and eight blue T-shirts. He also has two blue, three brown and five black jackets.

What is the probability that Mikel will be wearing the same colour T-shirt and jacket?

• $$\frac{13}{20}$$

• $$\frac{13}{200}$$

• $$\frac{21}{20}$$

• $$\frac{37}{200}$$

Multiple Choice

You roll a fair dice.

Find the probability of rolling a 3 or an even number.

• $$\frac{1}{3}$$

• $$\frac{2}{3}$$

• $$\frac{1}{2}$$

• $$\frac{5}{6}$$

Multiple Choice

A spinner has sectors in different colour. The probability of landing on red, blue and gold are 35%, 20%, and 10% respectively.

Find the probability on landing on neither blue or gold.

• 25%
• 50%
• 15%
• 70%