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5.03 Estimating probabilities

Worksheet
Experimental probability
1

What term refers to the subcollection of the outcomes of an experiment?

2

What is the sum of the probabilities of all possible outcomes of an experiment?

3

A coin was flipped 184 times with 93 heads recorded. Find the experimental probability of flipping heads with this coin.

4
1000 computers were tested at a factory with 15 found to be faulty. Find the experimental probability that a computer at this factory will be faulty.
5

James watched cars drive past his house over five minutes. In this time 19 cars went by, and 7 of those cars were white. Find the experimental probability of a car being coloured white.

6

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?

7

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 without looking.

8

Hermione rolled a die 60 times.

a

How many times would he expect a six to appear?

b

After she finished rolling the die, she noticed that she had rolled a six 54 times. Find the experimental probability of getting a six.

9

A die is rolled 100 times. The results are shown in the given table:

Express the probability that the die rolls a 5 as a:

a

Fraction

b

Decimal

c

Percentage

ResultFrequency
114
212
311
413
514
636
10

A die is rolled 121 times with the results in the given table:

Find the experimental probability of:

a

Rolling a 5 with this die.

b

Rolling a 4 or higher with this die.

c

Rolling a 4 or lower with this die.

NumberFrequency
120
219
319
420
521
622
11

The given table presents the results of multiple coin tosses:

HeadsTails
Frequency5248
a

How many times was the coin tossed?

b

Find the relative frequency of tossing a head.

c
Find the experimental probability of tossing a tail.
d

If the coin was tossed 600 times, how many times would you expect it to land on a head?

e

If the coin was tossed 800 times, how many times would you expect it to land on a tail?

12

A card is randomly selected and replaced from a normal deck of cards multiple times. The outcomes are shown in the given table:

Using these outcomes, calculate the relative frequency of selecting:

a

A diamond.

b

A club.

c

A heart.

d

A spade.

e

A black card.

f

A red card.

Suit DrawnFrequency
\text{Diamond}15
\text{Club}15
\text{Heart}10
\text{Spade}11
\text{Total}51
13

Consider the histogram showing the outcomes of a coin toss experiment:

a

How many times was the coin tossed?

b

What was the relative frequency of tossing heads?

14

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

a

How many times was the die rolled?

b
Find the experimental probability of rolling a 2.
c

Find the relative frequency of not rolling a 3.

d

Find the experimental probability of rolling an even number.

OutcomeFrequency
113
212
320
414
515
616
15

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

a

Find the experimental probability of not rolling a number less than 3.

b

Find the relative frequency of not rolling a prime number.

c

Find the sum of the relative frequencies of rolling a 1, 2, 3, 4, 5 and 6.

d

Find the sum of the experimental probabilities of rolling an even number and of rolling an odd number.

OutcomeFrequency
116
216
319
413
512
612
16

The table shows the outcomes of tossing three coins multiple times:

a

How many times were the three coins tossed?

b

Find the experimental probability of tossing:

i

3 tails.

ii

At least 2 heads.

iii

At least 1 tail.

iv

Only 1 head.

v

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
17

If the probability of an event occurring is \dfrac{11}{25}, how many times would you expect the event to occur in 575 trials?

18

Sixteen dice were rolled and a 2 occurred on four of the dice.

a

What was the relative frequency of rolling a 2?

b

How many times would you expect a 2 to occur if 48 dice are rolled?

19

Three students were trying to determine the probability of every possible outcome when three coins are tossed. They tossed the coins and recorded the following results:

a

Find the relative frequency of getting 2 heads and a tail.

b

The students expect that if they toss the coins many more times, the probability of each outcome will become \dfrac{1}{4}.

Is this correct? Explain your answer.

OutcomeNumber of trials resulting in outcome
\text{A: } 3 \text{ heads}13
\text{B: } 2 \text{ heads and a tail}34
\text{C: } 2 \text{ tails and a head}40
\text{D: } 3 \text{ tails}17
20

A coin is tossed 100 times and the results are presented in the table below. How many times would you expect the coin to land on a tail if the coin was tossed:

a

400 times.

b

500 times.

c

600 times.

d

920 times.

HeadsTails
Frequency4456
21

Uther decided to flip a coin 14 times.

a

How many times would he expect a tail to appear?

b

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

c

Explain why the experimental probability and Uther's expectation of getting tails is not the same.

22

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.

Applications
23

At a particular traffic light, it was found that the light in a particular direction stays green for 119 seconds, yellow for 5 seconds and red for 76 seconds.

If a car approaches the traffic light, find the probability, as a percentage, that the light will be:

a

Green

b

Yellow

c

Red

24

The following table shows the frequency of the lengths jumped at a long jump competition. The class interval is a range of distances measured in centimeters:

a

Find the probability that someone jumped more than 119\text{ cm}.

b

Find the probability that someone's jump measured between 80 and 159\text{ cm}(inclusive).

Class IntervalFrequency
0 -396
40- 799
80 - 1197
120 - 1598
160 - 1991
200 - 2392
\text{Sum}33
25

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

What was the relative frequency of a lamb meal being ordered?

MealFrequency
\text{Chicken}25
\text{Beef}41
\text{Lamb}44
\text{Vegetarian}46
26

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 2 claims.

Number of claims made012
Number of policy holders131219
27

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

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

a

89 toothpicks.

b

More than 90 toothpicks.

c

Less than 90 toothpicks.

Number of toothpicksNumber of Boxes
870
886
894
901
911
922
931
28

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
29

An insurance company found that in the past year, of the 750 claims made, 375 of them were from drivers under the age of 25. According to this data, find the experimental probability of a claim being made by:

a

Someone under the age of 25.

b

Someone 25 years or over.

30

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 Taekwondo 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{Taekwondo}59
31

The table shows the number of trains that arrived on time at a particular station from Monday to Friday:

a

What was the relative frequency of on time trains on Monday?

b

What was the greatest relative frequency of on time trains on any day of the week?

c

What was the relative frequency of on time trains over the entire week?

DayNumber of trainsOn time
\text{Monday}2822
\text{Tuesday}2111
\text{Wednesday}2117
\text{Thursday}2310
\text{Friday}2310
32

Each player draws as many domino as they like from a bag. A domino has two numbers from 1 to 6 on it as shown below. A high value domino occurs if the sum of its two numbers is greater or equal to 6. Otherwise it is a low value domino.

The table below shows how many dominoes each player has, and how many of them have a high value:

PlayerNo. of dominoes drawnNo. of dominoes drawn that are high value
\text{Sam}55
\text{Kristen}61
\text{Aoife}76
\text{Yan}54

A player wins by randomly selecting a low value domino from their drawn sample. Which player has the lowest chance of winning?

33

1000 transistors were tested at a factory, and 12 were found to be faulty.

a

Find the experimental probability that a transistor at this factory will be faulty.

b

If another 5000 transistors were tested, how many of these would you expect to be faulty?

34

Random selections were made from a set of cards labelled from 1 to 7.

\\

The table shows the results:

a

How many selections were made in total?

b

Find the experimental probability of drawing a 3.

c

Find the experimental probability of not drawing an odd number.

d

Find the relative frequency of drawing a number greater than 4.

e

If 1000 random selections were made, how many times would you expect to draw a number divisible by 5?

OutcomeFrequency
155
261
359
464
563
661
755
35

During tennis practice, a coach focused on his player's forehands. He found that 19\% were hit into the net, 10\% were hit out of the court, and the remainder were hit in the court.

a

What percentage of the player's forehands were hit in the court?

b

If the player hit 200 forehands during the practice session, how many went into the net or out of the court?

36

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.

37

Georgia is drawing a card out of a deck of 10 cards, labeled from 1 to 10. She drew a card and returned it 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 the 6 card 6 times. Find the experimental probability of getting the 6 card.

38

At a golf course, the number of golf balls lost each day over several days were recorded, and rounded to the nearest 10. The table shows the results:

Using the data, estimate the probability that more than 39 golf balls will be lost tomorrow.

Number of Golf Balls LostNumber of Days
105
205
301
404
503
39

The following table shows the number of people who scored a certain mark on a recent test. The test is marked out of 50.

a

Find the probability that someone scored more than 50 \% on the test.

b

Find the probability that someone scored between 21 and 40 inclusive.

Class (Marks)Frequency
11-155
16-201
21-256
26-302
31-354
36-409
41-4510
46-503
\text{Total}40
40

The following table shows the weekly wage of a number of workers that were surveyed:

a

Estimate the probability that a worker chosen from the sample has a wage of at least \$280 per week.

b

Find the probability that a worker chosen from the sample has a wage of more than \$294.

Weekly wages in dollarsFrequency
220-2345
235-2493
250-2642
265-2792
280-29410
295-3092
310-3242
\text{Total}26
41

The following frequency table shows the number of people that came to donate blood and their respective weights:

a

If this group is considered to be representative of the population, find the probability that someone in the population weighs 50 to 54\text{ kg}.

b

Find the probability that someone weighed between 60 and 69\text{ kg}. inclusive?

\text{Weight in kg}\text{Frequency }
40-442
45-493
50-542
55-591
60-648
65-698
70-745
\text{Total}29
42

The graph shows the four countries that university students applied to for exchange in the last month:

a

What is the relative frequency of the country with the fewest applications?

b

If the monthly applications are the same throughout the year, how many people will apply for UK over the next 12 months?

43

This frequency graph shows the number of people that were served at a furniture store, and the length of time it took to serve them:

a

Find the probability that someone was served in under 40 minutes.

b

Find the probability that someone had to wait at least 50 minutes to be served.

44

The following frequency graph shows the heights of people that were surveyed at a particular rollercoaster ride in a theme park:

a

Estimate the probability that someone randomly chosen at the park was between 130 and 149 \text{ cm} tall.

b

Find he probability that someone randomly chosen was at most 129 \text{ cm} tall.

45

The size of several earthquakes was measured over a period of time and the results are presented in the graph:

a

Estimate the probability that an earthquake will measure 5, 6, or 7.

b

Estimate the probability that an earthquake measures less than 5.

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Outcomes

1.3.2.4

use relative frequencies obtained from data as point estimates of probabilities

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