Jack and Ben had a bicycle on which they went to a neighborhood village. They rode it in turns, but whenever one rode, the other walked and did not run. They managed to arrive in the village at the same time and almost twice as fast than if they had both walked. How did they do it?
Three tourists must move from one bank of the river to another. At their disposal is an old boat, which can withstand a load of only 100 kg. The weight of one of the tourists is 45 kg, the second – 50 kg, the third – 80 kg. How should they act to move to the other side?
Try to decipher this excerpt from the book “Alice Through the Looking Glass”:
“Zkhq L xvh d zrug,” Kxpswb Gxpswb vdlg, lq udwkhu d vfruqixo wrqh, “lw phdqv mxvw zkdw L fkrrvh lw wr phdq – qhlwkhu pruh qru ohvv”.
The text is encrypted using the Caesar Cipher technique where each letter is replaced with a different letter a fixed number of places down in the alphabet. Note that the capital letters have not been removed from the encryption.
Write a number instead of the space (in letters, not numbers!) to get a true sentence:
THIS SENTENCE HAS ... LETTERS
(Note that the dash does not count as a letter, i.e. the word twenty-two is made up of 9 letters).
Dave spent the first Tuesday of the month in Bath, and the first Tuesday after the first Monday in Cardiff. The following month Dave spent the first Tuesday in London, and the first Tuesday after the first Monday in Cambridge. Can you determine what month and date Dave was in each of the cities?
Alice the fox and Basilio the cat are counterfeiters. Basilio makes coins heavier than real ones, and Alice makes lighter ones. Pinocchio has 15 identical in appearance coins, but one coin is fake. How can Pinocchio determine who made the false coin – Basilio the cat or Alice the fox – with only 2 weighings?
Once Alice was in one of two countries – A or Z. She knows that all of the residents of country A always tell the truth, and all the inhabitants of country Z always lie. Moreover, they often go to visit each other. Can Alice, after asking a single question to the first person that she meets, find out which country she is in?
In a cup, glass, jug and jar there is milk, lemonade, cola and water. It is known that the water and the milk are not in the cup; the container with the lemonade stands between the jug and the cola container; the jar does not contain lemonade or water; the glass stands near the jar and the container with milk. Which container is filled with each of the liquids?
In the equation \(101 - 102 = 1\), move one digit in such a way that that it becomes true.
When three friends – Nina, Helen and Anna – went out for a walk, they were wearing white, red and blue dresses. Their shoes were of the same three colors, but only Nina had the same shoe and dress color. At the same time, neither Helen’s dress, nor her shoes were blue, and Anna was wearing red shoes. Determine the color of the dresses and of the shoes of each friend.