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7.02 Experimental probability

Worksheet
Experimental probability
1

At a factory, 1000 computers were tested with 15 found to be faulty. Calculate the experimental probability that a computer selected at random at this factory will be faulty.

2

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 that the next car will be coloured white.

3

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

4

A fair coin was flipped 100 times with 51 tails recorded. Find the experimental probability of flipping tails with this coin.

5

A coin was tossed 50 times. It landed on tails 4 times. Each toss was recorded. Out of these recorded tosses, find the probability of selecting one that landed on tails. Express your answer as a decimal.

6

After flipping a fair coin 70 times, the relative frequency of heads is found to be \dfrac{52}{70}.

a

Find the probability of the next flip being a tail.

b

If the experiment were to be repeated an infinite number of times, what fraction would you expect the relative frequency of heads to be?

7

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

8

A traffic light tester finds that every 60 seconds, a certain traffic light remains green for 21 seconds, yellow for 3 seconds and red for 36 seconds. Find the experimental probability of the following events:

a

Arriving at the traffic light when it is green.

b

Arriving at the traffic light when it is yellow.

c

Arriving at the traffic light when it is red.

9

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.

10

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

a

Express the experimental probability that a 5 is rolled as a:

i

Fraction

ii

Decimal

iii

Percentage

b

If the die is rolled an infinite amount of times, express the probability that a 5 is rolled as a decimal, correct to two decimal places.

ResultFrequency
114
212
311
413
514
636
c

Calculate the absolute difference between the experimental and theoretical probability of rolling a 5.

11

A die is rolled 60 times and the results are recorded in the following table:

a

Find the experimental probability of:

i

Rolling a 6 with this die.

ii

Rolling a 3 or higher with this die.

iii

Rolling a 3 or lower with this die.

b

If the die is rolled an infinite amount of times, express the probability that a 3 or higher is rolled as a decimal, correct to two decimal places.

ResultFrequency
110
212
38
410
58
612
c

Calculate the absolute difference between the experimental and theoretical probability of rolling a 3 or higher.

12

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
13

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
14

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
15

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

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
16

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

a

Calculate the relative frequency of selecting:

i

A diamond.

ii

A club.

iii

A heart.

iv

A spade.

v

A black card.

vi

A red card.

Suit drawnFrequency
\text{Diamond}15
\text{Club}15
\text{Heart}10
\text{Spade}11
\text{Total}51
b

If the experiment was repeated an infinite amount of times, find the expected relative frequency of selecting:

i

A heart.

ii

A black card.

17

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 trains that were on time on Monday?

b

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

c

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

DayNumber of trainsOn time
\text{Monday}2822
\text{Tuesday}2111
\text{Wednesday}2117
\text{Thursday}2310
\text{Friday}2310
18

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

a

How many times was the coin tossed?

b

Find the relative frequency of tossing a head.

19

The column 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?

20

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
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Outcomes

4.1.2

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

4.1.5

recognise the law of large numbers and identify relative frequency as probability

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