100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

What have one eye but still cannot see?

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

What English word has three consecutive double letters?

What does this say?

XLR8

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

What 5-letter word typed in all capital letters can be read the same upside down?

What is the fastest way to double your money?