If the inscription on the red door were true, the others would also be true. If the blue door were the path to freedom, all inscriptions would be false. Therefore, the answer is green door.

The lines are: Red: Freedom is behind this door. Blue: Freedom is not behind this door. Green: Freedom is not behind the blue door.

To solve this we take multiple cases: First: Inscription on red door is true in that case next two cases must be false, but this option does not give us a sure answer. Second: In this case we consider the inscription on blue to be true then third would also be true but this also does not give a specific answer. Third: In this case let us assume that inscription on green is true and also that on red is false then the answer would be GREEN.

Therefore the answer is GREEN door.

Assume Freedom is behind the red door. All three doors would then have true statements which we know is not possible since one of them must be false.

Assume Freedom is behind the blue door. All three doors would then have false statements which we know is not possible since one of them must be true.

Freedom is therefore behind the green door. The blue door and the green door have true statements and the red door has a false statement

source: edcollins.com

Blue and Green are saying the same thing, so the two doors must have the same truth values. Since we're told that "at LEAST ONE of the three statements on the three doors is true and at LEAST ONE of them is false", then Red must have the opposite truth value than the others.

Since the path to freedom is only through one door, then we can't change a supposedly false non-freedom door into being the second supposedly true freedom door, so it's definitely the case of a False Red door against 2 True doors.

Then, the scenario at hand is that the freedom door is neither the Red one (which lied about being one) nor the Blue one (which told the truth about it not being one), so therefore the real path to freedom must lies behind the Green Door.

Situation A-red door is true. Therefore, the green door is also true (freedom is not behind the blue door). Furthermore, the blue door is also true. However, there must be at least ONE false statement, and therefore the red door is not true. If the red door is true, logic breaks.

Situation B-blue door is true Therefore, the green door is also true. Red door we can assume is false, since there must be at least one false statement and because of Situation A's result. The only door left is the green one. If the blue door is true, then the green door leads to freedom.

Situation C-green door is true Therefore, the blue door is also true. In addition to this, the red door can either be true or false, but we'll assume it's false because of the reasons mentioned above. The only door left, once again, is the green one. If the green door is true then it leads to freedom.

Alternative solution: Have the boys each walk through a different door. This way at least one of them will survive. After all,

Opening a door to dragon means almost certain death.

(italics mine) so the unlucky boys might be able to survive.

The logic to the problem analogy is very much simple. Given that the amongst the three statements ,atleast one in True and atleast one is False,which implies 1) we can have two true statements and a false statement
OR 2)we can have two false statements and a true statement

Right ?? Yes ..

Drawing out conclusion from the truth values of each statement gives the result

T ->Truth F-False

RED   |   BLUE     |  GREEN   |      CONCLUSION

1) T | T | F SInce Green and Blue statements are contradictory,the freedom door might be Red or green .Lets see another case....

2) T F F The freedom door might be red or green ..Not blue because the green and blue's statement do not contradict

3) T F T if the green is speaking truth,but you see blue's statement is a contradictory to blue's statement.the freedom door might be red or green.

4) F T T Green's and Blue's Statement do not contradict with each other.Chances are the freedom door might be green or blue

5) F T F green's statement is false.but blue's statement is correct a conflict between the two.the freedom door might be in green

6) F F T if green is speaking the truth,then blue statement must be a truth but here its a contradiction.The door might be green

Evidences that shows that Red is the freedom door : 3 Evidences that shows that Blue is the freedom door : 1 Evidences that shows that Green is the freedom door: 6

So Pretty much I would go for Green

Both green and blue says freedom is not behind the blue door.. So red door's statement s false.. So result of these two leads to green door.

It is very simple logic Green signal is always sign of good . Inscription on red door is true in that case next two cases must be false, but this option does not give us a sure answer . In this case we consider the inscription on blue to be true then third would also be true but this also does not give a specific answer . Therefore Green is correct

Red door is false. Blue door won't lead them to safety. Green door is correct.

Consider Blue & Green door statements are correct and Red door is false. All other possibility will give absurd answer.

The statements on blue and green doors necessarily have the same truth value, so we only have two statements. From the given assumption, we need one to be correct and the other incorrect.

If the statement on red door is correct, then the statement on blue door is incorrect, and thus freedom is behind two doors, red and blue. This is impossible. So the statement on red door is incorrect and the statement on blue door is correct.

Thus freedom is not behind red door (red door has incorrect statement), not behind blue door (blue door has correct statement), and thus must be behind green door .