Which of the following are sets ? Justify your answer.
The collection of ten most talented writers of India.
The collection of ten most talented writer of India is not a well-defined collection because the criteria for determining a writer's talent vary from person to person.
Hence, this collection is not a set.
Write the following as intervals :
$\{ x:x \in R,0\, \le \,x\, < \,7\} $
Write the following sets in roster form :
$D = \{ x:x$ is a prime number which is divisor of $60\} $
In the following state whether $\mathrm{A = B}$ or not :
$A = \{ x:x$ is a multiple of $10\} ;B = \{ 10,15,20,25,30 \ldots \ldots \} $
Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$\varnothing \subset A$
Write the following sets in the set-builder form :
$\{ 2,4,6 \ldots \} $