How many subsets with exactly 2 elements does A = {1, 2, 3, 4} have? Call the number N.
Sets, relations & functions worksheet with answers
1.Easy
A = {1, 2, 3, 4}
N =
2.Easy
Exactly one region of the Venn diagram is the set A′ ∩ B. Click its number.
A′ ∩ B
- 1region 1
- 2region 2
- 3region 3
- 4region 4
3.Medium
The relation R on {1, 2, 3, 4} is drawn as a directed graph (a loop means (x, x) ∈ R). Exactly one of the four properties holds. Click it.
R = {(1, 1), (1, 2), (1, 3), (2, 2), (2, 3), (3, 1), (3, 3), (3, 4), (4, 4)}
- 1reflexive
- 2symmetric
- 3antisymmetric
- 4transitive
4.Medium
Of 56 first-year students, 27 passed Mathematics (M), 24 passed Physics (P) and 30 passed Chemistry (C). 13 passed M and P, 8 passed M and C, 16 passed P and C, and 6 passed all three. How many are in none of the three sets?
|U| = 56
|(M ∪ P ∪ C)′| =
5.Hard
How many antisymmetric relations are there on a set with 3 elements? Call the number N.
|X| = 3
N =
6.Hard
How many injective (one-to-one) functions f: A → B are there if |A| = 2 and |B| = 3? Call the number N.
|A| = 2|B| = 3
N =
Answer key
- 1. N = 6
- 2. region 4
- 3. reflexive
- 4. |(M ∪ P ∪ C)′| = 6
- 5. N = 216
- 6. N = 6
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