How many subsets of A = {1, 2, 3, 4} contain neither 4 nor 1? Call the number N.
Sets, relations & functions worksheet with answers
The Venn diagram shows every element of the universal set U and of the sets A and B. Find |(A − B)′|, the number of elements of (A − B)′.
In a group of 72 students, 32 speak French (F), 36 speak German (G) and 31 speak Spanish (S). 16 speak French and German, 10 French and Spanish, 12 German and Spanish, and 5 speak all three. How many are in none of the three sets?
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.
- 1reflexive
- 2symmetric
- 3antisymmetric
- 4transitive
On X = {1, 2, …, 12} the relation x ~ y holds when x ≡ y (mod 5). How many elements are in the equivalence class [5]?
How many bijections f: A → B are there if |A| = |B| = 3? Call the number N.
Answer key
- 1. N = 4
- 2. |(A − B)′| = 7
- 3. |(F ∪ G ∪ S)′| = 6
- 4. symmetric
- 5. |[5]| = 2
- 6. N = 6
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