Jamia Millia Islamia MCA 2017
Let cardinality of set A and B are 2 and 5 respectively. The number of relations from A to B is
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Answer: Option A — 1024
Detailed Solution
.
A relation from to is any subset of : .
✓ Check
If , has 1 pair and the relations are and that pair: .⚠ Common trap
(D) 1025 adds 1 for the empty relation, which is already one of the subsets.Quick tip
Relations from to
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Relations & Mappings — Preparation
This question tests your understanding of Relations & Mappings, a key topic in the Quantitative Aptitude section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
A relation from set A to set B is a subset of the Cartesian product A x B. A mapping, or function, is a special relation in which every element of A is related to exactly one element of B. This topic covers types of relations (reflexive, symmetric, transitive and equivalence relations), domain, codomain and range, and types of functions such as one-one (injective), onto (surjective) and bijective functions, along with composition and inverse functions. Exam questions test identifying the type of a given relation or function, counting the number of relations or functions between two sets, and finding the domain or range of a function. Useful counting facts: if A has m elements and B has n elements, there are 2^(mn) relations and n^m functions from A to B. Practise the relations and mappings questions below, each with a step-by-step solution.