Replace the question mark with the correct number in the below-given picture?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

I don't get anymore wetter, no matter how much rain falls on me.

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

Can you find the mistake in the below statement?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.