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?

Which is faster, Heat or Cold ? Explain.

Find the next number in the series below

21 32 54 87 131 ?

No matter how little or how much you use me, you change me every month. What am I?

What is the next number in this series?

4,12,84,3612....

There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

A kind heart person buy packed food at 3$/packet from United states and sells them at 1$/packet at Africa. After some time he becomes a millionaire.

How come the guy become millionaire ?

Can you find a five letter word that is left with only two letters if one is removed?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.