Question 1065512
a)   Since each answer can be true or false, there are 2 ways to answer each question.   
There are 2x2 = 4 ways [(T,T), (T,F), (F,T), (F,F) ] to answer two questions. 
Extending this reasoning to all seven questions,  there are 
           {{{highlight(2^7 = 128)}}} ways to answer all seven questions.


b)  To get no questions wrong: there is only {{{highlight(7C0 = 1)}}} way for that to happen.
      To get one question wrong: there are {{{highlight(7C1 = 7)}}} ways for that to happen.
      To get two questions wrong:  there are {{{ highlight(7C2 = 21) }}} ways for that to happen.


c)  This part makes use of (a) and (b), can you solve?
I will give you a couple hints:   
  Hint1:  Pr{5 or more correct} = Pr { 2 or fewer incorrect} 
  Hint2:  Think number of ways X can happen, divided by total number of ways to answer all seven.
  Hint3:  0.2265625