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7.025 Theoretical probability

Worksheet
Theoretical probability
1

The following standard die is rolled:

a

Find the probability of rolling a four.

b

Find the probability of rolling a one.

c

Find the probability of rolling an odd number.

2

A 12-sided die has faces with the numbers 1 through 12 as shown:

a

Find the probability of rolling an odd number.

b

Find the probability of rolling a multiple of 4.

3

The box shown contains 3 yellow balls, 4 red balls, 1 white ball, and 2 striped balls:

Iain selects one ball without looking.

a

Find the probability that Iain selects:

i

A red ball.

ii

A white ball.

iii

A yellow ball.

iv

A striped ball.

b

Which type of ball is Iain most likely to select?

4

Paul has 23 marbles in a bag and 4 of them are black. Paul picks a marble from the bag without looking. Find the probability that Paul picks a black marble.

5

Jack has a bag of marbles with 5 marbles. 4 of those marbles are red. Express the probability that Jack picks a red marble as a decimal number.

6

A single marble is drawn from the following jar which contains 5 red, 7 blue and 8 black marbles:

a

Find the probability of drawing a blue marble. Express your answer as a percentage.

b

Find the probability of drawing a blue marble or a red marble. Express your answer as a percentage.

7

Yuri has a bag of marbles with 10 marbles. 1 of those marbles is blue. Express the chance of Yuri picking a blue marble as a percentage.

8

Dylan has 32 marbles in a bag, and 20 of them are orange. Find the probability Dylan will pick a orange marble from the bag.

9

A jar contains 10 marbles in total. Some of the marbles are blue and the rest are red.

a

If the probability of picking a red marble is \dfrac{4}{10}, how many red marbles are there in the jar?

b

Find the probability of picking a blue marble.

10

Each 26 letters of the alphabet are written on separate pieces of paper and placed in a bag. If one letter is to be picked out of the bag at random, find the probability of picking a:

a

J

b

K, Y or R

c

Letter in the word PROBABILITY

d

M, K, D, O, H or B

e

Letter in the word WORKBOOK

f

Vowel

11

A number is randomly selected from the following list:

\left\{1, \, 3, \, 3, \, 6, \, 6, \, 6, \, 8, \, 8, \, 8, \, 8, \, 10, \, 10, \, 10, \, 10, \, 10\right\}

a

Find the probability of selecting a 1.

b

Find the probability of selecting a 3.

c

Find the probability of selecting an 8.

d

Which number is most likely to be selected?

12

Amy picks a whole number between 4 and 8 inclusive.

a

List the sample space.

b

Find the probability that Amy picked the number 5.

c

Find the probability that Amy picked the number 1.

d

Find the probability that Amy picked an even number.

13

A book has pages numbered from 1 to 100. If the book is opened to a random page, find the probability that the page number:

a

Is a multiple of 9.

b

Has the digit 6 in the page number.

14

The following spinner has 8 equal sectors. 3 sectors are purple, 2 sectors are red, 2 sectors are yellow, and 1 sector is blue:

Determine the probability it lands on:

a

Purple.

b

Blue.

c

Yellow.

15

Consider the following spinner:

Find the probability of spinning:

a

A pig.

b

A ball or a pig.

c

A pig or an apple.

d

An apple or a star.

16

For each of the following spinners, find the probability of the spinner landing on a star. Express your answer as a percentage.

a
b
c
d
17

The following spinner has 10 equal sectors. 4 sectors are blue, 3 sectors are red, 2 sectors are green, and 1 sector is yellow:

a

Express as a decimal the probability it lands on red.

b

Express the probability it lands on blue as a simplified fraction.

c

Express the probability it lands on blue as a percentage.

d

Express the probability it lands on blue as a decimal.

18

Charlene spins the spinner shown:

a

List the sample space.

b

Find the probability of spinning a number greater than 29.

c

Find the probability of spinning a number in the twenties.

d

Find the probability of spinning a 27 or a 29.

19

Consider the following spinner:

a

Find the probability of getting the following shapes. Simplify your answers.

i

An apple.

ii

A pig.

iii

An elephant.

iv

A ball.

v

A pig or a ball.

vi

Anything but an apple.

vii

An elephant, a star or a bear.

viii

Anything but a ball or a bear.

b

Determine whether the following events have a probability less than 10\%:

i

Spinning a bear.

ii

Spinning a star.

iii

Spinning an apple.

iv

Spinning a ball or an elephant.

20

A circular spinner is divided into three unequal parts. The green sector takes up an angle of 250 \degree at the centre. The red sector takes up an angle of 60 \degree at the centre and the blue sector takes up the remainder of the spinner.

Find the probability that the spinner will land on blue.

21

A card is drawn from a standard deck of cards:

Find the probability that the card is:

a

A diamond or spade.

b

A picture card (King, Queen or Jack).

c

A spade or a red card.

d

The Jack of Hearts or the Jack of Clubs.

22

Rosey draws a 6 of Spades from a regular pack of cards and puts the card back in the deck. She then asks you to draw a card. Find the probability that you will draw a card with a number larger than 6, and the same colour as Rosey's card.

23

The table below shows the number of times each policy holder made an insurance claim over a 1-year period:

a

How many claims were made altogether?

b

If one policy holder is chosen at random, find the probability that they made two claims.

Number of claims made012
Number of policy holders131219
24

High school students attending an international conference were asked to register what language other than English they speak. The results are shown in the table:

a

How many students attended the conference?

b

Find the probability that a student chosen at random speaks:

i

French

ii

Mandarin

iii

Arabic or Spanish

iv

Spanish or Other

LanguageFrequency
\text{French}20
\text{Arabic}13
\text{Spanish}21
\text{Mandarin}19
\text{Other}37
25

A cube has six faces, each face is painted a certain colour. If the cube is rolled, find the number of faces that should be painted blue so that the probability of blue appearing on the uppermost face is:

a

\dfrac{1}{2}

b

\dfrac{1}{3}

c

\dfrac{1}{6}

d

1

26

Consider the following four numbered cards:

Two of the cards are randomly chosen and the sum of their numbers is listed in the following sample space:

\left\{15,\, 10, \, 8, \, 11, \, 9, \, 4\right\}

a

Find the missing number on the fourth card.

b

If two cards are chosen at random, find the probability that the sum of their numbers is:

i

Even

ii

At least 10

27

A three-digit number is to be formed from the digits 4, 5 and 9, where the digits cannot be repeated.

a

List all the possible numbers in the sample space.

b

Find the probability that the number formed is:

i

Odd

ii

Even

iii

Less than 900.

iv

Divisible by 5.

Complementary events
28

For each of the following, state whether the two events are complementary:

a

Event 1: Selecting a positive number.

Event 2: Selecting a negative number.

b

Event 1: Drawing a red card from a standard deck of cards (no jokers).

Event 2: Drawing a black card from a standard deck of cards (no jokers).

c

Event 1: Drawing a club from a standard deck of cards (no jokers).

Event 2: Drawing a spade from a standard deck of cards (no jokers).

d

Event 1: Rolling a number greater than 3 on a die.

Event 2: Rolling a number less than 3 on a die.

e

Event 1: Rolling a number greater than or equal to 2 on a die.

Event 2: Rolling a 1 on a die.

29

For each of the following probabilities, state the probability of the complementary event:

a

\dfrac{4}{5}

b

62\%

c

0.64

d

\dfrac{3}{27}

30

A biased coin is flipped, with heads and tails as possible outcomes. Calculate P \left( \text{heads} \right) if P \left( \text{tails} \right)=0.56.

31

The sample space of an event is listed as S = \left\{\text{short}, \text{average}, \text{tall}\right\}. If P \left( \text{average} \right)=0.5 and P \left( \text{short} \right)=0.3, find P \left( \text{tall} \right).

32

A number between 1 and 100 inclusive is randomly picked.

a

Describe the complement of picking a number greater than 61.

b

Find the probability that the number picked is greater than 61.

33

A bag contains 34 red marbles and 35 blue marbles. If picking a marble at random, find:

a

P \left( \text{red} \right)

b

P \left( \text{not red} \right)

c

P \left( \text{blue} \right)

d

P \left( \text{red or blue} \right)

34

A bag contains 50 black marbles, 37 orange marbles, 29 green marbles and 23 pink marbles. If a marble is selected at random, find the following probabilities:

a

P \left( \text{orange} \right)

b

P \left( \text{orange or pink} \right)

c

P \left( \text{not orange} \right)

d

P \left( \text{neither orange nor pink} \right)

35

A regular die is rolled. Find the probability of:

a

Rolling a 4.

b

Not rolling a 4.

c

Not rolling a 1 or 5.

d

Not rolling an even number.

e

Not rolling an 8.

f

Not rolling a 1,\,2,\,3,\,4,\,5, or 6.

36

The 26 letters of the alphabet are written on pieces of paper and placed in a bag. If one letter is picked out of the bag at random, find the probability of:

a

Not selecting a B.

b

Not selecting a K, R or T.

c

Selecting a letter that is not in the word PROBABILITY.

d

Not selecting a T, L, Q, A, K or Z.

e

Selecting a letter that is not in the word WORKBOOK.

37

On a production line, it was found that foods packaged contained trace amounts of nuts with relative frequency of 0.37. What percentage did not contain trace amounts of nuts?

38

A group of students were surveyed on their eye colour. The results are shown in the table:

a

Find the probability that a student has eyes that are not brown. Express your answer as a percentage.

b

Calculate the percentage of students that had hazel eyes.

c

Calculate the least number of students that could have completed the survey.

BrownBlueGreenHazel
70\%15\%2\%
39

A card is drawn at random from a standard deck. Find the probability that the card is:

a

A diamond.

b

A spade.

c

Not a heart.

d

Not a seven.

40

From a normal deck of cards, find the probability of:

a

Selecting a five.

b

Not selecting a five.

c

Selecting a nine.

d

Not selecting a two.

e

Selecting a black card.

f

Not selecting a black card.

41

A card is selected from a standard deck of cards:

Find the probability of:

a

Selecting a face card.

b

Selecting a black nine.

c

Selecting an odd-numbered black card, not counting ace as a numbered card.

d

Selecting a red nine.

e

Not selecting a red three.

f

Not selecting a queen of clubs.

g

Selecting a ten, jack, queen, king or ace.

h

Selecting the king of diamonds.

i

Not selecting a red ten or black jack.

42

A bag contains 86 marbles, some of them are black and some are white. If the probability of selecting a black marble is \dfrac{33}{43}, find:

a

The number of black marbles.

b

The number of white marbles.

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Outcomes

4.1.2

describe ways of expressing probabilities formally using fractions, decimals, ratios and percentages

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