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Einstein’s Famous Riddle
Einstein’s Riddle, also known as the Zebra Riddle, is a very famous puzzle, and it is said that only 2% of the population could solve it. Rumoured to have been written by Einstein as a boy, the mysterious true author of the riddle contains a line-up of geniuses, including famed author Lewis Carroll.
The Puzzle
There are 5 houses in a row, each painted a different colour. A person of a different nationality lives in each house. These 5 owners keep different pets, drink different beverages, and enjoy playing different activities. The question is: Who owns the fish? Can you solve Einstein’s Riddle using the following clues?
- The British man lives in the red house.
- The Swedish man keeps dogs as pets.
- The Danish man drinks tea.
- The German plays soccer.
- The green house’s owner drinks coffee.
- The owner who plays baseball has birds.
- The owner who plays basketball lives next to the one who keeps cats.
- The Norwegian lives in the first house.
- The owner who plays the violin drinks beer.
- The owner of the yellow house plays the piano.
- The owner living in the center house drinks milk.
- The owner who keeps the horse lives next to the one who plays the piano.
- The green house is on the immediate left of the white house.
- The Norwegian lives next to the blue house.
- The owner who plays basketball lives next to the one who drinks water.
| House | 1 | 2 | 3 | 4 | 5 |
| Nationality | |||||
| Colour | |||||
| Pet | |||||
| Drink | |||||
| Plays |
Feedback
There are more than one way of doing these puzzles and may well be more than one answer. Please let me and others know what alternatives you find by commenting below. We also welcome general comments on the subject and any feedback you'd like to give.
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Last month's solutions
Puzzle One
In a sequence of six numbers, every term after the second term is the sum of the previous two terms. Also, the last term is four times the first term, and the sum of all six terms is 13. What are the six numbers in the sequence?
Solution:
Let the first and second terms be ‘a’ and ‘b’ respectively. Then our sequence can be written as follows:
a, b, (a + b), (a + 2b), (2a + 3b), and (3a + 5b)
Since the last term is four times our first term, then the 6th term becomes:
3a + 5b = 4a, or a = 5b and our sequence can now be written as:
5b, b, 6b, 7b, 13b, and 20b.
And as stated, sum of all six terms is 13, therefore 52b = 13 or b = 13/52, ¼ or 0.25
Then, the 1st term is (5 x b = 1.25) and the sequence of the six terms will then be:
1.25, 0.25, 1.5, (6 x 0.25), (13 x 0.25) + (20 x 0.25)
Therefore, the 6 terms and their sequence are: 1.25, 0.25, 1.5, 1.75, 3.25, 5.0, and to verify solution, their sum equals 13.
Puzzle Two
In a certain triangle the size of each of the angles is a whole number and the angle of one is 30⁰ larger than the average of the other two angles. What is the largest possible size off an angle in this triangle?
Solution:
Let a = the average o two of the three angles
Then, 2a + (a + 30⁰) = 180⁰
3a = 180⁰ – 30⁰ = 150⁰
a = 50⁰
and therefore, the sum of these two angles = 100⁰ and the largest possible whole number would be 99⁰ (i.e., 99⁰ & 1⁰ with average = 50⁰).
Puzzle Three
A two-digit number ‘ab’ is multiplied by its reverse ‘ba’. In its four-digit product, the ones and tens digits are both 0. What is the value of the smallest two-digit number ‘ab’??
Solution:
Since the one’s and ten’s digits of the product are both zero, either a or b must be 5.
If b = 5, then ‘a’ must be even and since the product ends in ‘00’, it must be a multiple of 100 ending in 5. The smallest 2-digit multiple of 100 ending in 5 is 25. Therefore, ‘ab’ is equal to 25 and to verify the solution, 25 x 52 = 1200.