1Describe the four regions of a two-set Venn diagram and say what each contains.
2Why must you always fill in the overlap of a Venn diagram first?
3In a group of 50, 30 read a newspaper, 22 listen to the radio and 12 do both. Work out all four regions and check your answer.
4How do you shade a Venn diagram to show A − B, and how does this show that A − B and B − A are different?
5Why is checking that the four regions add up to n(U) worth doing every time?