Determine whether there is a one-to-one correspondence between the two sets. {Mon, Tue, Wed} and

Question

{Oct, Nov, Dec}

Answer 1

Two sets have a one-to-one correspondence between them when they have the same cardinality, i.e. number of distinct members in each set. (note: by definition of a set, all members of a set are distinct).
The cardinality of both sets are 3, so the answer is yes.