Question

2. If n(A) =20, n(AUB)=39, n(ANB)=9 then n(B)=?​

Answer 1

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Given that -

n(A) = 20

n(A U B) = 39

n(A ∩ B) = 9

To Find -

n(B) = ?

Solution :

Using the Formula ,

n(A U B) = n(A) + n(B) - n(A ∩ B)

39 = 20 + n(B) - 9

39 = 11 + n(B)

n(B) = 39 - 11

n(B) = 28

So, the answer is 28