Question

Given, $P=\{a,b,c,e\},$ $Q=\{b,c,d,f\}$ and $R=\{c,f,h,i,j\}$. Number of elements of the set $P\cap Q\cap R$ is

Answer 1

Only c is common in all three sets P, Q and R

$\therefore P\cap Q\cap R=\left\{c\right\}$

$\Rightarrow n(P\cap Q\cap R)=1$