The answer to the “4 prisoner hat riddle” is Prisoner 2.
4 PRISONER HAT RIDDLE EXPLANATION :
Each one of the prisoners knows that there are 4 hats, 2 black, and 2 white.
If prisoner 1 observes that prisoners 2 and prisoners 3 have the same colored hats, he would assume that he has the opposite color and solve the riddle.
However, since prisoners 2 and prisoners 3 have different colored hats, prisoner 1 doesn’t say anything.
Prisoner 2 sees that he and prisoner 3 have different hats and realizes that prisoner 1 doesn’t know the answer. And since he sees that prisoner 3 has a white hat, he realizes that his own hat is black.