P(at least one wrong) = 1- P(all correct) =1-.25^6=1-1/4096=4095/4096. This assumes that the answers are picked at random. This kind of question is always the complement of an extreme binomial outcome.
so every 3 orange picks there are 2 green picks so 6 orange picks leads to 4 green pick and just keep adding to each side. 9 orange picks is 6 green picks, 12 orange picks is 8 green picks. Therefore you add 3 to 12 and get 15 which means 15 orange picks is your answer.
