1. The Number of Elements in a Finite Set
Section 6.2
The Number of Elements in a Finite Set

2. The Number of Elements in a Set
The number of elements in a set A is denoted n(A).
Ex. Given
n(A) = 4
Since the union doesn’t count a and h twice
Notice
This leads to
Overlap is subtracted

3. Venn Diagram U B A We can see that So Which leads to
– number of elements U 22 B A 5 12 31
We can see that So
Which leads to

4. Survey In a survey of 100 people at a carnival: 40 like cotton candy
30 like popcorn
45 like lemonade
15 like lemonade and popcorn
10 like cotton candy and lemonade
12 like cotton candy and popcorn
5 like all three
How many people don’t like lemonade, popcorn, or lemonade?
How many people only like popcorn?

5. Survey U P L n(C) = 40, n(P) = 30, n(L) = 45 C n(U) = 100
set C: cotton candy, set P: popcorn, set L: lemonade U P L 10 8 25 5 7 5
n(C) = 40, n(P) = 30, n(L) = 45 23 C 17
n(U) = 100
8 people only like popcorn.
17 people don’t like lemonade, popcorn, or lemonade.