There is a table on which 20 coins are placed. You also know that there are 10 coins with heads up, and 10 coins with tails up. You are blind folded and there is no way to determine which side is up by rubbing, etc.

Your task is to create two groups of coins, each having the same number of heads and tails. You may only move or flip coins. How can you accomplish this while being blindfolded?

If a doctor gives you three pills, telling you to take one every half hour, how many minutes will pass from taking the first pill to the last pill?

An old auto is to drive a stretch of 2 miles, up and down a hill. Because the auto is so old, you cannot drive the first mile (the ascent) faster than 15 miles per hour.

How fast do you have to drive the second mile (going down the hill) in order to get an average speed of 30 miles per hour?

Once upon a time there was a beautiful princess named Anna. Anna’s father, the King, wanted to be sure his daughter married an intelligent man.

To test his daughter’s suitors the King hid Anna’s picture in one of three boxes. The suitor had to be able to select the box with Anna’s picture on one try and within twenty seconds.

The following messages were written on the boxes.

Gold box: Anna’s picture is in this box.
Silver box: Anna’s picture is not in this box.
Bronze box: Anna’s picture is not in the gold box.

The King would tell each suitor, “Only one of the three messages is correct.” Which box contained Anna’s picture?