Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

What always comes into a house through the keyhole?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

Which digit occurred maximum times between the number 1 and 1000?

The first box has two white balls. The second box has two black balls. The third box has a white and a black ball.

Boxes are labeled but all labels are wrong!

You are allowed to open one box, pick one ball at random, see its colour and put it back into the box, without seeing the colour of the other ball.

How many such operations are necessary to correctly label the boxes?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

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?