Difficult riddles

logicshort

Difficult pop quiz

A teacher decides to give a pop quiz one day but all of her students refuse to take the quiz thinking that the teacher will call off the quiz. She can give only one of these students a detention for skipping the quiz. All of the students know each other's names and if a student knows he/she is getting a detention they take the quiz. How can she threaten her students with the single detention so they all take the quiz?
She tells them that she will give the student who skips the quiz whose name comes first alphabetically a detention. This student won't skip because they know they are getting a detention if they do. The next person alphabetically will then know that they will get a detention so they won't skip either, and so on.
75.65 %
84 votes

logicmathprobability

In a supermarket

In a supermarket, the first 25 customers of the day purchased an average of two items each. After a further 15 customers, the average number of items purchased by each customer rose to eight. What was the average number of items purchased by the last 15 customers only?
18
70.70 %
40 votes

cleanEinstein’slogic

Gardens

Five friends have their gardens next to one another, where they grow three kinds of crops: fruits (apple, pear, nut, cherry), vegetables (carrot, parsley, gourd, onion) and flowers (aster, rose, tulip, lily). They grow 12 different varieties. Everybody grows exactly 4 different varieties Each variety is at least in one garden. Only one variety is in 4 gardens. Only in one garden are all 3 kinds of crops. Only in one garden are all 4 varieties of one kind of crops. Pears are only in the two border gardens. Paul's garden is in the middle with no lily. Aster grower doesn't grow vegetables. Rose grower doesn't grow parsley. Nuts grower has also gourd and parsley. In the first garden are apples and cherries. Only in two gardens are cherries. Sam has onions and cherries. Luke grows exactly two kinds of fruit. Tulips are only in two gardens. Apples are in a single garden. Only in one garden next to the Zick's is parsley. Sam's garden is not on the border. Hank grows neither vegetables nor asters. Paul has exactly three kinds of vegetable. Who has which garden and what is grown where?
Hank: pear apple cherry rose
Sam: cherry onion rose tulip
Paul: carrot gourd onion rose
Zick: aster rose tulip lily
Luke: pear nut gourd parsley
67.20 %
110 votes

logicshortwhat am I

If I'm not alone

Alone I am 24th, with a friend I am 20. Another friend and I am unclean. What am I?
The letter 'X'. It is the 24th letter of the alphabet, XX in Roman numerals is 20, and XXX is a label for movies that are very inappropriate (unclean).
64.34 %
178 votes

logicmathshort

The sequence

1 11 21 1211 111221 312211 What is the next number in the sequence?
The next number it: 13112221. Each number describes the previous number. Starting with 1, the second line describes it 11 (one 1). Then the third line describes 11 as 21 (two 1's). Then the fourth line describes 21 as 1211 (one 2, one 1). This is the pattern.
64.05 %
106 votes

cleanEinstein’slogic

Ships in a port

There are 5 ships in a port. The Greek ship leaves at six and carries coffee. The ship in the middle has a black chimney. The English ship leaves at nine. The French ship with a blue chimney is to the left of a ship that carries coffee. To the right of the ship carrying cocoa is a ship going to Marseille. The Brazilian ship is heading for Manila. Next to the ship carrying rice is a ship with a green chimney. A ship going to Genoa leaves at five. The Spanish ship leaves at seven and is to the right of the ship going to Marseille. The ship with a red chimney goes to Hamburg. Next to the ship leaving at seven is a ship with a white chimney. The ship on the border carries corn. The ship with a black chimney leaves at eight. The ship carrying corn is anchored next to the ship carrying rice. The ship to Hamburg leaves at six. Which ship goes to Port Said? Which ship carries tea?
The French ship.
62.74 %
105 votes