GCSE · Venn diagrams & set notation

Probability from Venn diagramsExam-style questions

Why the denominator is always the total in the universal set — outsiders included — where P(A ∪ B) = P(A) + P(B) − P(A ∩ B) comes from in the picture, and how a "given that" condition shrinks the denominator to one circle.

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11 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAll Level 1 Level 2 Level 3 Level 4 Level 5

1
$40$ adults were asked whether they own a cat ( $C$ ) and whether they own a dog ( $D$ ). The Venn diagram shows the results.One of the $40$ adults is chosen at random.

(a) Find the probability that this adult owns a cat.

(b) Find the probability that this adult owns neither a cat nor a dog.
Level 2 · 3 marksTry it