Since two of them are the same, you have a 50% chance of picking something that is 33% of the possible answers. The other two, you have 25% chance of picking something that us 33% of the possible answers.
So 50%33% + 2 (33%*25%)= 33%
So your chances of being right is 33% cause there is effectively 3 choices.
Since two of them are the same, you have a 50% chance of picking something that is 33% of the possible answers. The other two, you have 25% chance of picking something that us 33% of the possible answers.
So 50%33% + 2 (33%*25%)= 33%
So your chances of being right is 33% cause there is effectively 3 choices.
But that one answer has a 33% larger possibility of being chosen by random, than the remaining two.
I covered that by multiplying it by 50% as it represents 50% of the choices.