Question

If X and Y are two sets such that $n\left(X\right)=45,n(X\cup Y)=76,n(X\cap Y)=12,$ find $n\left(Y\right)$.

• A. $41$
• B. $43$
• C. $49$
• D. $47$

Answer 1

Answer: (B)

$43$

$n(X\cup Y)=n\left(X\right)+n\left(Y\right)-n(X\cap Y)$

$76=45+n\left(Y\right)-12$

$n\left(Y\right)=43$