Problems

Age
Difficulty
Found: 1936

Along the path between Fiona’s and Jane’s house there is a row of flowers: 15 peonies and 15 tulips in a random order. Before visiting Fiona’s house, Jane started watering all of the plants from the beginning of the row. After the 10th tulip the water finished and 10 flowers were left unwatered. The next day, before visiting Jane’s house, Fiona started picking flowers for a bouquet starting from the end of the row. After picking the 6th tulip, she decided that the bouquet was big enough. How many flowers were left growing beside the path?

In a herd consisting of horses and camels (some with one hump and some with two) there are a total of 200 humps. How many animals are in the herd, if the number of horses is equal to the number of camels with two humps?

After a circus came back from its country-wide tour, relatives of the animal tamer asked him questions about which animals travelled with the circus.

“Where there tigers?”

“Yes, in fact, there were seven times more tigers than non-tigers.”

“What about monkeys?”

“Yes, there were seven times less monkeys than non-monkeys.”

“Where there any lions?”

What is the answer he gave to this last question?

The graph of the function \(y=kx+b\) is shown on the diagram below. Compare \(|k|\) and \(|b|\).

Some inhabitants of the Island of Multi-coloured Frogs speak only the truth, and the rest always lie. Three islanders said:

Bree: There are no blue frogs on our island.

Kevin: Bree is a liar. She herself is a blue frog!

Clara: Of course, Bree is a liar. But she’s a red frog.

Are there any blue frogs on this island?

In the family of happy gnomes there is a father, a mother and a child. The names of the family members: Alex, Charlie and Jo. At the dinner table two gnomes made two statements.

Charlie said: “Alex and Jo are of different genders. Alex and Charlie are my parents”.

Alex said: “I am Jo’s father. I am the daughter of Charlie”.

Who is who? That is, what is the name of the father, the mother and the child, if it is known that each gnome lied once, and each told the truth once.

On the first day of school, in all three of the first year classes (1A, 1B, 1C), there were three lessons: Maths, French and Biology. Two classes cannot have the same lesson at the same time. 1B’s first lesson was Maths. The Biology teacher praised the students in 1B: “You have even better marks than 1A”. 1A’s second lesson was not French. Which class’s last lesson was Biology?

There are bacteria in a glass. After a second each bacterium divides in half to create two new bacteria. Then after another second these bacteria divide in half, and so on. After a minute the glass is full. After how much time will the glass be half full?

Anna, Vincent, Tom and Sarah each bought one apple for 10p from a fruit stand. How did they manage to do this, if they didn’t have any coins less than 20p and if the fruit stand didn’t have any change less than 50p?