Which number should replace the question mark?

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?

There are six people in a family namely M, N, O, P, Q and R.

R and O are brother and sister.

N is the brother of Q's husband.
P is the father of M and grandfather of R.

How many male members are in the family?

I have no life, but I can die. What am I?

Mother's Name is Mrs. SIXTY TWO
Son's Name is FIFTY TWO
Daughter's Name is FORTY TWO
What is Name of Father?

who is silent in the parliament?

What has one eye, but can’t see?

What is black when you buy it, red when you use it, and gray when you throw it away?

Through your logical capabilities, can you make 7 an even?

What number comes next in this sequence:
7 8 5 5 3 4 4 _