Nine passengers carried with them enough food for five days. Several other passengers joined the first group and they all shared the same food, which was now enough for three days. How many passengers joined the first group?

A pole is 20 m high. An ant is climbing it as follows - every day she ascends 5 m and every night she descends 4 m. In how many days will the ant be on the top of the post?

A butcher had to stick a total number of 50 sheep in a week. Every day he sticked an equal number of sheep and managed to fulfill the task. How many sheep did he kill per day?

In a strange village an odd horse race took place. The goal was to have your horse cross the finish line last, not first. But when the race started all contestants refrained their horses from running. Then an old man came, asked to racers to get off and approach him. He said something to them and immediately after that they jumped on the horses again and the race began. What did the wise man tell the contestants?
(place mouse pointer over ? icon to view hints or answer requirements)

Question 10:

In a basket there are three sorts of apples. How many apples do you have to take from the basket to make sure you have at least 2 apples of the same sort?