M is the sister of N, and P is a child of N. How is P related to M?

Explanation

1. 01

   P is a child of M's brother or sister N, so P is M's nephew if P is a boy and M's niece if P is a girl.

2. 02

   The statements never say whether P is male or female.

3. 03

   Two families fit the facts and give different answers, so the relation cannot be determined.