Can You Solve a Brainteaser That Not Even Computers Understand?

We at Think About Network are certain that people are still way more intelligent than machines. And we can prove this to you.
This brainteaser is sometimes offered to people on computer courses — it’s possible for human beings to resolve, but no machine can ever work it out. Here it is:
How old are these 3 sisters, if:
  • Multiplying their ages gives a figure of 36;
  • Adding their ages together gives 13;
  • The oldest sister is blonde.
So did you work it out?

If multiplying their ages gives 36, then their ages have to be one of the following eight combinations:
36 = 2 × 3 × 6, and adding these ages together gives us 11.
36 = 2 × 2 × 9, and adding these ages together gives us 13.
36 = 4 × 9 × 1, and adding these ages together gives us 14.
36 = 4 × 3 × 3, and adding these ages together gives us 10.
36 = 18 × 2 × 1, and adding these ages together gives us 21.
36 = 12 × 3 × 1, and adding these ages together gives us 16.
36 = 6 × 6 × 1, and adding these ages together gives us 13.
36 = 36 × 1 × 1, and adding these ages together gives us 38.
We are left with two possible answers, since 2 + 2 + 9 = 13, as does 6 + 6 + 1. This is where the seemingly useless comment that “the oldest sister is blonde” turns out to be useful. This statement indicates that there is an older sister who doesn’t have a twin. In turn, only the first equation fits. Therefore, the answer is that the oldest sister is 9 years old and the younger ones are both 2.
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