We have to find the set that represents S ∩ (P ∪ Q).
We start by listing the elements that are in P or in Q to write the set P ∪ Q:
[tex]\begin{gathered} P=\lbrace6,7,11,12,14\rbrace \\ Q=\lbrace4,7,12,15,20\rbrace \\ P\cup Q=\lbrace4,6,7,11,12,14,15,20\rbrace \end{gathered}[/tex]We now can intersect this last set with S, which will include only the elements that are both in P ∪ Q and S:
[tex]\begin{gathered} P\cup Q=\lbrace4,6,7,11,12,14,15,20\rbrace \\ S=\lbrace3,4,11,12,16\rbrace \\ S\cap(P\cup Q)=\lbrace4,11,12\rbrace \end{gathered}[/tex]Answer: S ∩ (P ∪ Q) = {4,11,12} [Fourth option]