The more of this there is, the less you see. What is it?

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

Take number 1000 and then add 20 to it.
Now add 1000 one more time.
Now add 30.
Now add 1000 one more time.
Now add 40.
Now add 1000 one more time.
Now add 10.

What is the total?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

Can you find out the number that should replace the question mark with a valid reason?

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?