Chapter 7.1, Problem 11E

(a)

To determine

To Find: The example of a set $A\subseteq R$ such that $\sup \left(A\right)=4\text{and}4\notin A$ .

(b)

To determine

To Find: The example of a set $A\subseteq Q$ such that $\sup \left(A\right)=4\text{and}4\notin A$ .

(c)

To determine

To Find: The example of a set $A\subseteq N$ such that $\sup \left(A\right)=4\text{and}4\notin A$ .

(d)

To determine

To Find: The example of a set $A\subseteq N$ such that $\sup \left(A\right)>4\text{and}4\notin A$ .