A Venn diagram is a way of grouping different items. These groups are known as sets. We have a set of golf clubs or a set of dishes – these are just groups of those items. We write a set using a ...

In set notation this is B = {1, 4, 9}. 30 people answered a survey about whether they have a dog or a cat. The Venn diagram shows the information from the survey. 13 people have got a dog.