A Venn diagram uses circles to show sets. Items in the overlap belong to both sets. Items outside the circles belong to neither.
If 21 students were asked, and 6 like only swimming, 4 like both swimming and music, 8 like only music, then 21 − 18 = 3 like neither. The number who like swimming is 6 + 4 = 10, including the overlap. Probabilities come from these counts: P(both) = 4/21.
Worked example
In a Venn diagram, set A only has 7, the overlap has 3 and set B only has 5. How many are in set A?
- Set A includes A only and the overlap.
- 7 + 3 = 10.
Answer:10
Key words
- set
- a group of items
- intersection
- the overlap: in both sets
- union
- in either set or both
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