Question:
Let A be the set of all even whole numbers less than 10.
(i) Write A in the roster from.
(ii) Fill in the blanks with the approximate symbol ∉ or ϵ :
(a) 0 …. A
(b) 10 …. A
(c) 3 …. A
(d) 6 …. A
Solution:
(i) Whole numbers are 0, 1, 2, 3, …
Even whole numbers less than 10 are 0, 2, 4, 6, 8, 9
So, A = {0, 2, 4, 6, 8}
(ii) (a) Here, A = {0, 2, 4, 6, 8}
Hence, 0 ∈ A
(b) Here, A = {0, 2, 4, 6, 8}
As 10 is not in a set A
Hence, 10 ∉ A
(c) Here, A = {0, 2, 4, 6, 8}
As 3 is not in a set A
Hence, 3 ∉ A
(d) Here, A = {0, 2, 4, 6, 8}
As 6 is in set A
Hence, 6 ∈ A