Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

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

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

Look at me. I can bring a smile to your face, A tear to your eye, Or even a thought to your mind. But, I can't be seen. What am I?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?

Using mathematical symbols like +, -, and x in order to make the equations correct. Replace # with the above-given symbols.

9 # 8 # 7 # 6 # 5 # 4 = 91

What goes up but never comes down?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I