Sets & Relations
Sets and Relations
nta_abhyas_2025
Grade 11

Question:

If $A$ is the set of even natural numbers less than 8 and $B$ is the set of prime numbers less than 7, then the number of relations from $A$ to $B$ are
$2^7$
$3^7$
$2^{7-1}$
None

Step-by-Step Solution

Key Concept: The number of relations from set $A$ to set $B$ is $2^{|A| \times |B|}$ since each relation is a subset of the Cartesian product.
Given $A = \{2, 4, 6\}$ and $B = \{2, 3, 5\}$, the Cartesian product $A \times B$ contains $3 \times 3 = 9$ elements. The total number of relations from $A$ to $B$ equals the number of subsets of $A \times B$, which is $2^9 = 512$.
Correct Answer: 512

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