15-1 Venn Diagrams

Things you should know:

• The letter n stands for the intersection of the two circles.
• The letter u stands for the union which is both of the circles.
• When there is a line over a letter that means it is a complement. This simply means that you want everything that is not under the line.
• Formula: n(A u B)=n(A)+n(B)-n(A n B). <------ It only tells you to not count the middle number of the circles twice.

Example 1: Find (A n B), (A u B), and the complement of A. A has 80 (first circle), B has 40 (second circle), intersection has 10, left over is 360, and the overall number is 890.

• (A n B) simply means what is in the middle. So (A n B) = 10.
• (A u B) simply means what does both of the circles (including the middle) add up to. So (A u B) = 130.
• The complement of A simply means everything except for A. So the complement of A = 400.

Amber :)