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?

10+10 and 11+11 can give you the same answer.

Explain how?

I am sure no one can have two things for dinner. what are they?

What has one eye, but can’t see?

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 ?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

What is red and smells like blue paint?

What is more useful when it is broken?

What number divided by 4 is the same as that number minus 4?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?