Question

Given that set A has 48 elements and set B has 21 elements, determine each of the following. (a) The maximum possible number of elements in AUB elements (b) The minimum possible number of elements in AUB elements (c) The maximum possible number of elements in AnB elements (d) The minimum possible number of elements in AnB elements

Answer 1

Answer:  The required answers are

(a) 69,  (b) 21,  (c) 21  and  (d) 0.

Step-by-step explanation:  We are given that the set A has 48 elements and the set B has 21 elements.

(a) To determine the maximum possible number of elements in A ∪ B.

If the sets A and B are disjoint, that is they do not have any common element. Then, A ∩ B = { }   ⇒   n(A ∩ B) = 0.

From set theory, we have

$n(A\cup B)=n(A)+n(B)-n(A\cap B)=48+21-0=69.$

So, the maximum possible number of elements in  A ∪ B is 69.

(b) To determine the minimum possible number of elements in A ∪ B.

If the set B is a subset of set A, that is all the elements of set B are present in set A. Then,  n(A ∩ B) = 21.

From set theory, we have

$n(A\cup B)=n(A)+n(B)-n(A\cap B)=48+21-21=48.$

So, the minimum possible number of elements in  A ∪ B is 21.

(c) To determine the maximum possible number of elements in A ∩ B.

If the set B is a subset of set A, that is all the elements of set B are present in set A. Then, n(A ∩ B) = 21.

So, the maximum possible number of elements in  A ∩ B is 21.

(d) To determine the minimum possible number of elements in A ∩ B.

If the sets A and B are disjoint, that is there is no common element in the sets A and B . Then,  n(A ∩ B) = 0.

So, the maximum possible number of elements in  A ∩ B is 0.

Thus, the required answers are

(a) 69,  (b) 21,  (c) 21  and  (d) 0.