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Home » If A and B are two sets such that n(A) = 23, n(b) = 37 and n(A – B) = 8 then find n(A ∪ B). Hint n(A) = n(A – B) + n(A ∩ B) n(A ∩ B) = (23 – 8) = 15.
If A and B are two sets such that n(A) = 23, n(b) = 37 and n(A – B) = 8 then find n(A ∪ B). Hint n(A) = n(A – B) + n(A ∩ B) n(A ∩ B) = (23 – 8) = 15.
RS Agarwal Class 11 Maths Sets
If A and B are two sets such that n(A) = 23, n(b) = 37 and n(A – B) = 8 then find n(A ∪ B). Hint n(A) = n(A – B) + n(A ∩ B) n(A ∩ B) = (23 – 8) = 15.

Given: n(A) = 23, n(B) = 37, n(A – B) = 8
Using the hint
n(A) = n(A – B) + n(A ∩ B)
⇒ 23 = 8 + n(A ∩ B)
⇒ n(A ∩ B) = 23 – 8
⇒ n(A ∩ B) = 15

Visualizing the hint given,
We know that n(A ∪ B) = n(A) + n(B) – n(A ∩ B)
⇒ n(A ∪ B) = 23 + 37 – 15
⇒ n(A ∪ B) = 45
Hence n(A ∪ B) = 45

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