# Fake coins - logic puzzle

Suppose you have five bags filled with the same type of coins and
a weigthing machine. One of this bags is completely filled with fake coins, the other bags contain only real ones. A real coin weights
10 gram and a fake one 11 gram. What is the minimal number of times you need to use the weighting machine in order to find the bag with the fake coins? |

# Also having birthday today? - math puzzle

Out of how many people should a group at least consist in order to have that the probability that two persons out of that group are having birthday on the same day, is larger than 1/2? |

# Billiard-balls - logic puzzle

Nine billiard-balls are lying in front of you. Except for one they all have the same weight. The exception is a little bit heavier than the others. What is the minimal number of times you have to use a balance in order to find the wrong billiard ball? |