Write the following as intervals :

$\{ x:x \in R,3\, \le \,x\, \le \,4\} $

List all the elements of the following sers :

$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $

Which of the following are sets ? Justify your answer.

The collection of all boys in your class.

Let $A$ and $B$ be two non-empty subsets of a set $X$ such that $A$ is not a subset of $B$, then

Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?

$1 \in A$

State whether each of the following set is finite or infinite :

The set of animals living on the earth