Let and define a relation on by if

MATHEMATICS · Single correct · CBSE · Mathematics · Relations and Functions · Relations and Functions

Problem

Let

S=\{1,2,3,\dots ,20\}

and define a relation

R

S

a\,R\,b

a\equiv b\pmod{3}

. How many elements are there in the equivalence class

[2]

? (a) 6 (b) 3 (c) 7 (d) 5