Question 779022
Need represent ALL the possibilities.  Four questions, two choices for each question, so how many possible combinations?  

1 question ------------- {{{2^1}}} combinations
2 questions ------------{{{2^2}}} combinations
3 questions ------------{{{2^3}}} combinations
4 questions ------------{{{2^4=16}}} combinations


How many combinations have three questions answered as TRUE?  You identified these combinations, so you should be all set to finish.