Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

You have two buckets - one holds exactly 5 gallons and the other 3 gallons. How can you measure 4 gallons of water into the 5 gallon bucket?

(Assume you have an unlimited supply of water and that there are no measurement markings of any kind on the buckets.)

Can you name four days which start with the letter 'T'?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?

What does the below rebus riddle means?

By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?