If A = 2, 3, 4, 5, 7 , B = 7, 8, 9 , then find n(A ∪ B). - Vidyadip

MCQ

If A = {2, 3, 4, 5, 7}, B = {7, 8, 9}, then find n(A ∪ B).

A
1
B
3
C
5
D
7

✓

Answer

7

Solution:

A = {2, 3, 4, 5, 7}

n(A) = 5

B = {7, 8, 9}

n(B) = 3

n(A ∩ B) = 1

$\therefore$ (A ∪ B) = n(A) + n(B) − n(A ∩ B)

(A ∪ B) = 5 + 3 − 1 = 7

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