Question

If A and B are two sets such that n(B) =12, n(AΠB) =4 and n(AUB) =29 then finds(A)

Answer 1

Answer:

Given:

• $n(B) = 12$
• $n(A \cap B) = 4$
• $n(A \cup B) = 29$
• $n(A) = ?$

Solution:

$\dag \underline{\mathcal{By \ formula :}}$

➣$n(A \cup B) = n(A) + n(B) - n(A \cap B)$

➣$29 = n(A) + 12 - 4$

➣$n(A) + 8 = 29$

➣$n(A) = 29 - 8$

$\boxed{\implies{\boxed{n(A) = 21}}}$