Why Aeroplane windows are round?

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

By using all numbers, i.e. 123456789 and subtraction/addition, operators number 100 can be formed in many ways.
Example: 98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100

But if we add a condition use of the number 32 is a must. Then there are limited solutions.
One of such solution is: 9 - 8 + 76 + 54 - 32 + 1 = 100

Can you tell me any other solution?

Do you know of a place where the wind blows south and then suddenly shifts direction towards the north?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Can you identify the direction in which this bus is moving; left or right?

Hint: The bus is moving on the roads of London.

I inserted a coin in a bottle and closed its mouth with the help of a cork. Now, I was able to take the coin out from the bottle without taking out the cork or breaking the bottle. Can you tell me how I did it?

Which alphabet letter is a question?