JEE PYQ: Sets And Relations Question 12
Question 12 - 2020 (07 Jan Shift 2)
Let $X = {n \in N : 1 \leq n \leq 50}$. If $A = {n \in X : n \text{ is a multiple of } 2}$ and $B = {n \in X : n \text{ is a multiple of } 7}$, then the number of elements in the smallest subset of $X$ containing both $A$ and $B$ is _________.
Show Answer
Answer: 29
Solution
$n(A) = 25, n(B) = 7$ and $n(A \cap B) = 3$
$n(A \cup B) = n(A) + n(B) - n(A \cap B)$
$= 25 + 7 - 3 = 29$
BETA
