1. A Π B = all elements in both sets A and B
Discrete Math Section 15.1 Use Venn Diagram, intersections, unions, and inclusion-exclusion principle to solve problems
Intersection of sets A and B
A Π B = all elements in both sets A and B
Union of sets A and B
A U B= all elements in either set A or B

2. If set A = { 1,2,3,4} and set B = {3,4,5,6} find the following: A U B
example
If set A = { 1,2,3,4} and set B = {3,4,5,6} find the following:
A U B
A Π B
n(A) = (number of elements in set A)
n(A U B)
n(A Π B)

3. Inclusion-Exclusion Principle: for sets A and B, n(A U B) = n(A) + n(B) – n(A Π B)
Of 58 seniors, 36 drive their own car to school, 42 are in extra-curricular activities, and 28 are in extra-curricular activities and drive their own car to school. How many don’t drive and are not in extra-curricular activities?

4. example
Of the 72 employees at SES, 42 are teachers and 31 employees live in Salina, If 26 teachers live in Salina, how many non-teacher employees do not live in Salina?

6. Empty set (null set) Ø has no elements
Universal set U is the set of all elements
Complement of set A ( ) is all elements in U but not in set A.
Example: If U = {1,2,3,….10} and A = {1,2,3…7}
Find

7. assignment
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Problems 1,2,4,6,8,11,12,14,19,20