Question

Out of $32$ persons $30$ invest in National Savings Certificates and $17$ invest in Shares. What is the number of persons who invest in both?

• A. $13$
• B. $15$
• C. $17$
• D. $19$

Answer 1

Answer: (B)

$15$

Let $A$ be the persons who invented in National Savings Certificate and $B$ be the person who invested in show.

$n\left(A\right)=30$

$n\left(B\right)=17$

$n(A\cup B)=32$

Number of person who invested in both$=n(A\cap B)$

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

$=30+17-32$

$=47-32$

$=15$

Number of person who invested in both $=15$