Paper 3 June 2023, Question 11 1 mark
A and B are mutually exclusive events.
Which one of the following statements must be correct?
Tick () one box.
Reveal mark scheme
AQA A Level Maths
Topic questions Statistics Mutually exclusive & independent events
6 questions · 37 marks · about 45 minutes
A and B are mutually exclusive events.
Which one of the following statements must be correct?
Tick () one box.
Also involves Sets and Venn diagrams
A sample of 240 households were asked which, if any, of the following animals they own as pets:
The results are shown in the table below.
| Types of pet | C | D | T | C and D | C and T | D and T | C, D and T |
| Number of households | 153 | 70 | 45 | 48 | 21 | 32 | 17 |
Represent this information by fully completing the Venn diagram below.
A household is chosen at random from the sample.
Find the probability that the household owns a cat only.
Find the probability that the household owns at least two of the three types of pet.
Find the probability that the household owns a cat or a dog or both, given that the household does not own a tortoise.
Determine whether a household owning a cat and a household owning a tortoise are independent of each other.
Fully justify your answer.
Also involves Sets and Venn diagrams
A and B are two events such that
Find P(A)
Find P(BA)
Determine if A and B are independent events.
Diedre is a head teacher in a school which provides primary, secondary and sixth-form education.
There are 200 teachers in her school.
The number of teachers in each level of education along with their gender is shown in the table below.
| Primary | Secondary | Sixth-form | |
| Male | 9 | 24 | 23 |
| Female | 35 | 85 | 24 |
A teacher is selected at random. Find the probability that:
the teacher is female
the teacher is not a sixth-form teacher.
Given that a randomly chosen teacher is male, find the probability that this teacher is not a primary teacher.
Diedre wants to select three different teachers at random to be part of a school project.
Calculate the probability that all three chosen are secondary teachers.
A survey was conducted into the health of 120 teachers.
The survey recorded whether or not they had suffered from a range of four health issues in the past year.
In addition, their physical exercise level was categorised as low, medium or high.
50 teachers had a low exercise level, 40 teachers had a medium exercise level and 30 teachers had a high exercise level.
The results of the survey are shown in the table below.
| Low exercise | Medium exercise | High exercise | |
| Back trouble | 14 | 7 | 10 |
| Stress | 38 | 14 | 5 |
| Depression | 9 | 2 | 1 |
| Headache/Migraine | 4 | 5 | 5 |
Find the probability that a randomly selected teacher:
suffers from back trouble and has a high exercise level;
suffers from depression.
suffers from stress, given that they have a low exercise level.
For teachers in the survey with a low exercise level, explain why the events ‘suffers from back trouble’ and ‘suffers from stress’ are not mutually exclusive.
A teacher in a college asks her mathematics students what other subjects they are studying.
She finds that, of her 24 students:
12 study physics 8 study geography 4 study geography and physics
A student is chosen at random from the class.
Determine whether the event ‘the student studies physics’ and the event ‘the student studies geography’ are independent.
It is known that for the whole college:
the probability of a student studying mathematics is
the probability of a student studying biology is
the probability of a student studying biology given that they study mathematics is
Calculate the probability that a student studies mathematics or biology or both.
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