How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

Can you place three balls such that the equation shown in the picture holds true?

Jack and Joseph are well-known golf rivals. One Day during a match, they were level at a score of 30. Jack hit a bad shot and Joseph added 10 to his score. Joseph then hit an awesome shot and he won the game.

How ?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

If,
29 - 1 = 30
9 - 1 = 10
14 - 1 = 15

Based on similar logic, Can you prove that the below algebraic equation is true?
11 - 1 = 10 ?

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

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

Can you spot the hidden girl in the picture below?

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?