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អ្នក​ពូកែ​គិត គំនិត​ទូលាយ​ ភ្ជាប់​នឹង​សំពាយ នៃ​ចំណេះ​ដឹង

How old are they?

Person x and y have the following conversation:

x: I forgot how old your three kids are.
y: The product of their ages is 36.
x: I still don’t know their ages.
y: The sum of their ages is the same as your house number.
x: I still don’t know their ages.
y: The oldest one has red hair.
x: Now I know their ages!

Answer:

From the statement that the product of their ages is 36 the possibilities of the three individual ages are:

1,1,36
1,2,18
1,3,12
1,4,9
1,6,6
2,2,9
2,3,6
3,3,4

From the statement that the sum equals the house number it is possible to eliminate all but two possibilities. The sums of the rest are unique and would allow for an immediate answer. For example if the house number were 16 the ages must be 1, 3, and 12. The two remaining possibilities are 2, 2, and 9; or 1, 6, and 6.

After the clue that the oldest has red hair you can eliminate 1, 6, and 6 because the oldest two have the same age thus there is no oldest son. The only remaining posibility is 2, 2, and 9.

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