Question

Which of the following sets can be the universal set for a set of all natural numbers.

• A. Set of all real numbers $R$
• B. Set of all integers $I$
• C. Set of all whole numbers $W$
• D. Set of all rational numbers $Q$

Answer 1

Answer: (A), (B), (C), (D)

Set of all rational numbers $Q$

Any set $A$ can be an universal set for any set B, iff $A$ is the superset of the set $B.$

This means all of the following sets can be the universal set for sets of all natural numbers $N$ as:
$N\subseteq W\subseteq I\subseteq Q\subseteq R$