i. A = set of multiples of 5
∴ A = {5, 10, 15, …}
B = set of multiples of 7
∴ B = {7, 14, 21,…}
C = set of multiples of 12
∴ C = {12, 24, 36, …}
Now, set of natural numbers, whole numbers, integers, rational numbers are as follows:
N = {1, 2, 3, …}, W = {0, 1, 2, 3, …}
I = {…,-3, -2, -1, 0, 1, 2, 3, …}
Q = {(p/q) | p,q ∈ I,q ≠ 0}
Since, set A, B and C are the subsets of sets N, W , I and Q.
∴ For set A, B and C we can take any one of the set from N, W, I or Q as universal set.
ii. P = set of integers which are multiples of 4.
P = {4, 8, 12,…}
T = set of all even square numbers
T = {22, 42, 62, …}
Since, set P and T are the subsets of sets N, W, I and Q.
∴ For set P and T we can take any one of the set from N, W, I or Q as universal set.