Question

If n(A-B)=5,m(A n B)=2 and n(B-A)=7 then find n(A U B).

Answer 1

Answer:

The answer is 14

Step-by-step explanation:

Formula:

    $\boxed{n(A-B)=n(A)-n(A\cap B), n(B-A)=n(B)-n(A\cap B)}$

Here given $n(A\cap B)=2$

And

 $n(A-B)=5\Rightarrow n(A)-n(A\cap B)=5\Rightarrow n(A)=5+2=7$

$n(B-A)=7\Rightarrow n(B)-n(A\cap B)=7\Rightarrow n(B)=7+2=9$

Therefore

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

                      $=7+9-2=16-2=14$