You are on the island of knights and knaves. There are only 2 kinds of people on this island, knights who always tell the truth and knaves who always lie.
You meet 7 people, Red, Orange, Yellow, Green, Blue, Black and White, who are all standing together. You know for a fact that 3 of them are knights and 4 are knaves. This is what they tell you.
Red says, "Black is a knight."
Yellow says, "Orange and I are of the same type. We either are both knights or are both knaves."
Blue says, "White and I are of different types."
Black says, "Green and I are of different types."
White says,"Red is a knight."
After hearing their statements, can you figure out which 3 of them are knights ?
Difficulty rating:
Easy-Medium. 5/10
Solution:
Case 1: Red is a knight. This would mean that Black is also a knight. This would make White a knight also as White would be telling the truth.
This would mean that Yellow, Orange, Blue and Green would all have to be knaves. However, notice that Yellow says that Orange and I are of the same type. Yellow would be telling the truth in this case despite being a knave.
In conclusion, Red cannot be a knight because then, Yellow would be telling the truth despite being a knave.
Thus, Red is a knave. This would mean that Black is also a knave. This would make Green a knave as well. And since White is saying that Red is a knight, which is a lie, it would make White a knave as well.
So, the 4 knaves are Red, Black, Green and White. The knights are Blue, Yellow and Orange.