Learning objective

Understand and apply the addition rule for probabilities, which states that P(A ∪ B) = P(A) + P(B) - P(A ∩ B).

Read the explanation, check the common trap, then practise with flashcards and questions.

Exam focus

Cambridge IGCSE StatisticsProbability

Study support

Understand this objective

Quick explanation

This point belongs to Probability, especially Probability outcomes.
You need to be able to understand and apply the addition rule for probabilities, which states that P(A ∪ B) = P(A) + P(B) - P(A ∩ B).
The key ideas to know are Explain and Describe.
Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.

Key concepts

ExplainDescribe

Why it matters

This objective helps connect Probability outcomes to exam-style questions, flashcards, and revision notes for Probability.

Revision tools

Flashcards10 linked cards

Flashcard 1 of 10

Press Space to flip, arrows to move

Practice Questions7 linked questions

Question 1 of 7

Choose an answer, get feedback, then move sideways through the set.

0 of 5 attempted

Paper 1Statistical Techniques3 marks

Description

Event A: Drawing a red ball Event B: Drawing a ball with a number Given probabilities: P(A) = 0.5 P(B) = 0.6 P(A ∩ B) = 0.3

a
Calculate Calculate the probability of drawing a ball that is either red or has a number on it (P(A ∪ B)).
Your answer
Aim for approximately 3 distinct marking points.
[3]

Revision notestopic notes

Open the full topic revision notes when you are ready to review this objective in context.

Revision hubs