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?
Find the missing numbers:
a) 4, 7, 12, 21, 38 ...;
b) 2, 3, 5, 9, ..., 33;
c) 10, 8, 11, 9, 12, 10, 13, ...;
d) 1, 5, 6, 11, 28, ....
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.
Is it always the case that in any 25 GBP banknotes – that is £5, £10, £20, and £50 notes – there will always be 7 banknotes of the same denomination?
Cowboy Joe was sentenced to death in an electric chair. He knows that out of two electric chairs standing in a special cell, one is defective. In addition, Joe knows that if he sits on this faulty chair, the penalty will not be repeated and he will be pardoned. He also knows that the guard guarding the chairs on every other day tells the truth to every question and on the alternate days he answers incorrectly to every question. The sentenced person is allowed to ask the guard exactly one question, after which it is necessary to choose which electric chair to sit on. What question can Joe ask the guard to find out for sure which chair is faulty?
Fred and George are twin brothers. One of them always tells the truth, and the other always lies. You can ask only one question to one of the brothers, to which he will answer “yes” or “no”. Try to find out the name of each of the twins.
In an ordinary set of dominoes, there are 28 tiles. How many tiles would a set of dominoes contain if the values indicated on the tiles did not range from 0 to 6, but from 0 to 12?