Chapter 13, Problem 4RE

To determine

To find: The value of $n\left(B\right)$ .

Answer to Problem 4RE

The value of $n\left(B\right)$ is $24$ .

Explanation of Solution

Given: $n\left(A\right)=12,n\left(A\cup B\right)=30,n\left(A\cap B\right)=6$ .

The value of $n\left(B\right)$ is calculated as,

  $\begin{array}{c}n\left(A\cup B\right)=n\left(A\right)+n\left(B\right)-n\left(A\cap B\right)\\ 30=12+n\left(B\right)-6\\ n\left(B\right)=36-12\\ =24\end{array}$