Replace the question mark with the correct number.

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

John was gifted a new Hayabusa. He drove x miles at 55mph. Then he drove x+20 miles at 40mps. He drove his bike for 100 minutes. How much distance did he travel?

There is something which you can be arrested for attempting but not for successfully completing.

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Count the number of squares in the picture below.

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?