Puzzle Details :
Jack is looking at Anne. Anne is looking at George. Jack is married, George is not, and we don’t know if Anne is married. Is a married person looking at an unmarried person?
Solution:
Why is this question so tricky?
It is because it appears to give you insufficient information. Anne’s marital status is not known, nor can it be determined, and so you make the inference that the question posed cannot be determined.
In fact, Anne’s marital status is irrelevant to the answer. If she is married, then a married person is looking at an unmarried person (Anne is looking at George), and if she isn’t, a married person is looking at an unmarried person (Jack is looking at Anne).
Written down it becomes more obvious. If ‘>’ means ‘looking at’ then:
Jack > Anne > George, or
Married > Unknown > Unmarried
Replace Unkown with Married or with Unmarried and either way there is clearly a married person looking at an unmarried one.
This puzzle really belongs more to psychology than it does to mathematics or logic, as it is about the lazy assumptions we make, rather than whether or not we have the ability to solve the question.
Yet the reasoning that is used - that in order to solve something we need to consider all possibilities without knowing which is true - is frequently used in maths.
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