Which of the following are sets? Justify your answer.

The collection of all rich persons of Kolkata.


As the collection of all rich persons of Kolkata may vary from person to person. Someone considers a person whose income is Rs 1 lakh per annum as a rich person, and someone considers a person whose income is Rs 1 crore per annum as a rich person. Here, the set is not well – defined.

, this is not a set


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