2. In the underwater kingdom, there live octopuses that can have 6, 7, or 8 legs. Those with 7 legs always lie, while the others always tell the truth. Upon meeting four octopuses, Blue said: "We have a total of 25 legs," Green countered: "No, there are 26 legs in total," Red said that the total number of legs is 27, and Yellow said 28. How many legs does each of the octopuses actually have?
Answer: Red has 6, the others have 7 each. Solution. If all four were lying, they would have 28 legs in total, and Yellow would be right - a contradiction. Therefore, there is a truthful one among the four. There is only one, as any two statements of the octopuses contradict each other. Therefore, three octopuses have 7 legs each, and one has 6 or 8. The latter is impossible, as then the octopuses would have 29 legs in total, while none of the octopuses mentioned such a sum. Therefore, the truthful one has 6 legs, and it is Red, who named the correct sum of 27.