#21 - In an experiment, subjects were shown a series of

[sammydz]

I do not think D has to be true.
this is my analysis of the paragraph: Say there are ten guessing options. actually, 6 were Top while 4 were bottom. these subjects guessed on a sequence they fabricated and were wrong at least six times. had they guessed Top all ten times, they would have been correct more than half (6 times).
answer D says that these subjects MUST HAVE INCORRECTLY GUESSED BOTTOM AT LEAST ONCE.
This seems to not be true. say they were correct all 4 times they guessed bottom, but incorrect every time it was actualy Top. had they guessed bottom every time it landed on top, and Top every time it was Bottom this would explain how on their random guessing patterns they were wrong more than half the time, but they still never guessed bottom incorrectly
Please explainleaseeIplain what i have mianalysismy analysis.

[Adam Tyson]

If they were incorrect each time it was at the top, then they must have guessed bottom, sammydz. Of course, this assumes that the only two options were either top or bottom, with no "middle" or "side" options, but that does seem to be implied in the stimulus. It would be nicer if it was explicit! If bottom and top are the only choices available, and they had to guess wrong at least once when it was at the top, then they must have guessed the bottom and been incorrect.