Immediately below this paragraph is a table
with links to the exam questions and answers for all the externals way back to 2013.
Focus on the exams for the last three years. Recognise the type of question e.g This is
a question about..... Know how you are going to set out your working when answering each type of question.
READ the question, all of it. There are key words in the questions which tell you what the
examiner expects
ANSWER the question. Often you are asked for your opinion. Give your opinion AND reasons to support
it
Notation and Symbols
In this exam you are expected to use the notation and language of probability
P(A) = the probability event 'A' occurs. This is the number of times 'A' happens (e.g patient
has diabetes) divided by the total number of events (the total number of patients)
P(A ∪ B) = the probability A or B occurs. The '∪' means 'union'
P(A ∩ B) = the probability A and B both occur. The '∩ means intersection
P(A | B) = the probability A occurs given that B has occurred (conditional probability)
P(Ā) = Probability 'not A'
Venn Diagrams
You have a good idea of how to compete Venn diagrams. Just remember
In your exam if there are three groups, you will probably have to construct a
Venn diagram
start with the number that are in all 3 sets.
there might be some that aren't in any of the groups. Their number goes outside the circles
So, Question 2a(i) from the 2021 exam
Tables
You are good at tables. In these questions you are given some of the totals, or some of the cells
and have to complete the missing cells or totals.
Remember to add extra rows and columns for the category names and the totals
When you are given two categories, the choice is most likely between a table and a tree
diagram
A tree diagram is for conditional probabilities such as 1/4 of those who smoke also vape
