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Grade 7

12.03 Theoretical and experimental probability

Worksheet
Theoretical probability
1

Yuri has 5 blue marbles, 1 red marble, 1 yellow marble and 1 black marble in a bag. Yuri picks a marble from the bag without looking. Find the probability that Yuri picks a blue marble.

2

A bag contains 21 red marbles and 26 blue marbles. Find the probability of drawing a red marble.

3

A bag contains 49 marbles. 24 of them are red and the rest are of them are blue.

Explain how to find the probability of drawing a blue marble.

4

A spinner has ten sectors of the same size:

  • 5 of the sectors show a star.

  • 2 of the sectors show an apple.

  • 3 of the sectors show an elephant.

Find the probability of spinning an elephant.

5

A letter is chosen at random from the word COCOONS.

a

Which letter is most likely to be chosen?

b

Find the probability that the chosen letter is a "C".

6

The numbers from 2 to 10 are written on separate cards. One card is chosen at random. Find the probability that the number is:

a

A multiple of 2.

b

A prime number.

c

A number less than 6.

7

A two-digit number is formed only using the digits 3 and/or 2.

a

List all the possible two-digit numbers.

b

Find the probability that the number formed is odd.

c

Find the probability that the number formed is more than 30.

8

A three-digit number is formed only using the digits 2, 7, and/or 8. Some of the possible three-digit numbers are listed below:

222, \quad 227, \quad 228, \quad 272, \quad 277, \quad 278, \quad 282, \quad 287, \quad 288, \\ 722, \quad 727, \quad 728, \quad 772, \quad 777, \quad 778, \quad 782, \quad 787, \quad 788
a

List the remaining possible three-digit numbers.

b

Find the probability that the number formed is odd.

c

Find the probability that the number formed is palandromic (the same forwards as backwards).

9

A full set of scrabble tiles is shown in the diagram below. The last two letters are the two "blank" tiles:

AAAAAAAAAB
BCCDDDDEEE
EEEEEEEEEF
FGGGHHIIII
IIIIIJKLLL
LMMNNNNNNO
OOOOOOOPPQ
RRRRRRSSSS
TTTTTTUUUU
VVWWXYYZ

One letter tile is drawn at random:

a

Find the probability that it is a "G" or an "R".

b

Find the probability of drawing a vowel.

10

Luigi and Danielle enter a raffle where 80 tickets are on sale. Luigi buys 1 ticket and Danielle buys 5 tickets.

a

Find the probability that Luigi wins if all the tickets were sold.

b

Find the probability that Danielle wins if all the tickets were sold.

c

Find the probability that Danielle wins if only 70 tickets were sold.

11

Consider the following dice:

Four-sided die

Six-sided die

Eight-sided die

Ten-sided die

Twelve-sided die

Twenty-sided die

State the die that would give the highest probability of rolling the following:

a

16

b

1

c

9

12

Emma rolls two four-sided dice and multiplies the two numbers she rolls together.

a

Find the probability that the number formed is even.

b

Find the probability that the number formed is larger than 6.

13

Neil takes the following cards and shuffles them up. He draws one card, shows it to you, and keeps it. You then draw one card from the remaining seven cards, and you win if the number on your card is higher than Neil's.

Find your chance of winning if Neil draws the following cards:

a
b
14

A fair die is rolled and then a coin is tossed.

a

What is the probability of getting an even number and a head?

b

What is the probability of getting an even number, a head, or both?

Multiple trials
15

A bag contains 28 red marbles, 27 blue marbles, and 26 black marbles.

a

Find the probability of drawing a blue marble.

b

A single trial is drawing a marble from the bag, writing down the colour, and putting it back. If this trial is repeated 400 times, how many blue marbles should you expect?

Round your answer to the nearest whole number.

16

A die is rolled 358 times.

a

If it lands on a six 12 times, what is the probability that the next roll will land on a six?

b

Does the outcome of the next roll depend on the outcome of previous rolls?

17

This spinner is spun 12 times. Find the number of times we would expect to spin:

a

An apple.

b

A ball.

18

If the probability of an event is \dfrac{2}{3}, how many times would you expect the event to occur in 18 trials?

19

A six-sided die is rolled 24 times. How many times should we expect to roll a 1?

20

An eight-sided die is rolled 24 times. How many times should we expect to roll a 7?

Round your answer to the nearest whole number.

21

A twenty-sided die is rolled 100 times. How many times should we expect to roll a 14 or more?

Round your answer to the nearest whole number.

Experimental probability
22

A retail store served 773 customers in October, and there were 44 complaints during that month.

Calculate the experimental probability that a customer complains. Give your answer as a percentage, rounded to the nearest whole percent.

23

Find the experimental probability of the following:

a
Flipping heads from a coin that was flipped 184 times with 93 heads recorded.
b

A computer being faulty at a factory where 1000 computers were tested and 15 were found to be faulty.

c

A car driving by is white, given that 1919 cars had gone by and 77 of them were white.

24

At a set of traffic lights, the green light is on for 24 seconds, then the yellow light lasts for 3 seconds, and then the red light is on for 13 seconds. This cycle then repeats continuously.

If a car approaches the traffic light, calculate the likelihood that the light will be:

a

Green

b

Yellow

c

Red

25

An insurance company found that in the past year, of the 2558 claims made, and 1493 of them were from drivers under the age of 25. Calculate the experimental probability, as a whole percentage, that a claim is filed by someone:

a

Under the age of 25.

b

25 years or older.

26

The experimental probability that a person uses public transport is 50\%. Out of 500 people, how many would you expect to use public transport?

27

Hermione rolled a standard six-sided die 60 times.

a

State the theoretical probability of rolling a six.

b

How many times would she expect a six to appear?

c

After she finished rolling the die, she noticed that she had rolled a six 24 times. Find the experimental probability of getting a six.

d

Were the theoretical and experimental probability of getting a six the same? Explain your answer.

28

A factory produces tablet computers. In March it produced 8000 tablets, and 240 were found to be faulty.

a

Calculate the experimental probability that a tablet produced by the factory is faulty.

b

The factory plans to produce 9000 tablets in April. How many should they expect to be faulty?

29

Uther flipped a coin 14 times.

a

How many times would he expect a tails to appear?

b

After flipping the coins, he noticed that tails had appeared 4 times. Find the experimental probability of getting a tails.

30

Derek spun the following spinner 20 times:

a

How many times would he expect the arrow to land on X?

b

After he finished spinning, he noticed that the arrow fell on X 8 times. Find the experimental probability of getting an X.

31

Oprah has a bag with 2 red balls, 2 blue balls, and 2 green balls in it. She took a ball out of the bag and returned it 24 times.

a

How many times would she expect to get a green ball?

b

After she finished, she noticed that she had drew a green ball 18 times. Find the experimental probability of getting a green ball.

32

Georgia is drawing a card out of a deck of 10 cards, labeled from 1 to 10. She drew a card and returned it to the bag 40 times.

a

How many times would she expect to get the card with 6 on it?

b

After she finished, she noticed that she had drew a 6 out of the bag 21 times. Find the experimental probability of getting a 6.

Tables
33

To prepare for the week ahead, a restaurant keeps a record of the number of each main meal ordered throughout the previous week.

a

How many meals were ordered altogether?

b

Calculate the experimental probability that a customer will order a beef meal.

Give your answer as a percentage, rounded to the nearest whole percent.

MealFrequency
\text{Chicken}54
\text{Beef}32
\text{Lamb}26
\text{Vegetarian}45
34

Five schools compete in a basketball competition. The results from the last season are given in the table below:

Schools competing each gameWinner
St Trinian's vs Ackley BridgeSt Trinian's
Ackley Bridge vs Summer HeightsSummer Heights
Lakehurst vs MarquessMarquess
Marquess vs St Trinian'sSt Trinian's
St Trinian's vs Summer HeightsSummer Heights
St Trinian's vs LakehurstLakehurst
Ackley Bridge vs MarquessAckley Bridge
Marquess vs Summer HeightsSummer Heights
Lakehurst vs Summer HeightsLakehurst
Ackley Bridge vs LakehurstLakehurst

Calculate the experimental probability that Ackley Bridge wins one of the matches.

35

The table shows the number of trains that arrived on time at the local station during the week:

a

Calculate the experimental probability that a train will be on time on Monday, as a whole percentage.

b

Which day had the highest experimental probability of a train being on time?

c

Calculate the experimental probability of a train arriving on time across the entire week, as a whole percentage.

DayNumber of trainsOn time
\text{Monday}2922
\text{Tuesday}2423
\text{Wednesday}2119
\text{Thursday}2722
\text{Friday}2320
36

The following table shows the outcomes of tossing three coins 102 times:

Find the experimental probability of:

a

Tossing 3 tails.

b

Tossing at least 2 heads.

c

Tossing at least 1 tail.

d

Tossing only 1 head.

e

Tossing exactly 2 tails.

OutcomeFrequency
\text{HHH}11
\text{HHT}12
\text{HTH}11
\text{HTT}16
\text{THH}12
\text{THT}15
\text{TTH}10
\text{TTT}15
37

Boxes of toothpicks are examined and the number of toothpicks in each box is recorded in the table shown:

If the number of toothpicks of another box were counted, find the experimental probability it will:

a

Contain 89 toothpicks.

b

Contain more than 90 toothpicks.

c

Contain less than 90 toothpicks.

Number of toothpicksNumber of Boxes
870
886
894
901
911
922
931
38

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

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
39

The table shows the results of rolling a die 90 times:

a

How many times was the die rolled?

b
What is the experimental probability of rolling a 2?
c

What is the experimental probability of rolling an even number?

OutcomeFrequency
113
212
320
414
515
616
40

The table shows the fighting style of each competitor in a mixed martial arts tournament fought last year:

a

Find the total number of competitors.

b

Find the experimental probability of a wrestler winning.

c

Find the experimental probability of a Kickboxing fighter not winning.

d

If 100 more competitors joined the competition, how many of them would you expect to use Karate as their fighting style?

EventFrequency
\text{Karate}40
\text{Wrestling}54
\text{Judo}47
\text{Kickboxing}59
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Outcomes

7.D2.2

Determine and compare the theoretical and experimental probabilities of two independent events happening and of two dependent events happening.

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