How many proper subsets does A = {1, 2, 3, 4} have (subsets other than A itself)? Call the number N.
Sets, relations & functions worksheet with answers
Exactly one region of the Venn diagram is the set A − B′. Click its number.
- 1region 1
- 2region 2
- 3region 3
- 4region 4
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
A survey of 51 people finds that 17 own a laptop (L), 28 a tablet (T) and 31 a smartwatch (W). 14 own L and T, 8 own L and W, 18 own T and W, and 6 own all three. How many are in none of the three sets?
The arrow diagram shows a function f: A → B with A = {1, 2} and B = {a, b, c, d, e}. Click the description that fits f.
- 1injective, not surjective
- 2surjective, not injective
- 3bijective
- 4neither
An equivalence relation R on {1, …, 10} has the classes {3, 8}, {1, 2, 10}, {4, 5, 6}, {7, 9}. How many ordered pairs does R contain? Call the number |R|.
Answer key
- 1. N = 15
- 2. region 1
- 3. reflexive
- 4. |(L ∪ T ∪ W)′| = 9
- 5. injective, not surjective
- 6. |R| = 26
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