Solution:
(i) A group of eleven of the world’s best cricket batsmen is not a well-defined collection.
Because the criteria used to determine a batsman’s talent differ from person to person.
As a result, this collection does not form a set.
(ii) The collection of all boys in your class can be considered as well-defined collection.
Because a boy who belongs to this collection can be identified .
As a result, this collection can be considered a set.