Question

Let sets A and B be defined as follows.

Answer 1

Given

• Set A: A = {-26, -25, -24, -23, - 22, - 21}
• Set B: B ∈ {x: x is even, x ≥ 6 and x ≤ 20}

(a)

Cardinality means the number of elements in the set.

Cardinality of the set A:

n(A) = 6, since we can count 6 elements.

Set B has even numbers between 6 and 20, both included:

• B = {6, 8, 10, 12, 14, 16, 18, 20}

Then its cardinality is:

• n(B) = 8

(b)

To solve this we need to compare the elements of sets A or B with numbers given:

• -22 ∈ A, True       ⇒  -22 is listed as element of A
• 6 ∈ B, True          ⇒  6 is listed as element of B
• - 21 ∉ A, False     ⇒  - 21 is listed as element of A
• 2 ∈ B, False         ⇒  2 is not listed as element of B