Suppose you have ten slow matches (also called match cord) and a lighter. If a slow match is lighted, it will burn for exactly one hour. The slow matches do not burn at constant speed, in other words it can happen that the first half of the slow match is burned in 15 minutes, while the remaining part will take three quarters. How can you measure exactly 45 minutes using these slow matches, and what is the minimum of slow matches you need for this?

To protect his country a king decided to build a wall made out of stone along the border. The wall had to be 3 meters thick and 5 meters high. The border of the country has a length of 500 kilometers. Assuming that one cubic meter of stone weights about 3000 kg, how much heavier becomes the earth by building this wall?

The local weatherman says No Rain, and his record is 2/3 accuracy of prediction. But the Federal Meteorological Service predicts rain, and their record is 3/4.

With no other data available, what is the chance of rain?