After testing alternate versions of the three successes (to see if those were based on luck), only two remain to be successful; Changing "The 2nd colour in purple, yellow, arm, white and blue is?" to "The 2nd colour in purple, arm, yellow, house, white and blue is?" causes the question to fail.
Good point. That gives a good indicator as to how the algorithm works. Not necessarily based on colors, but rather words in a list...? Maybe the construction of Text CAPTCHA sentences needs to be chosen carefully when thinking like an algorithm....
