SOLUTION: Assume that you are taking a seven ​-question true or false quiz. a. How many different ways are there to answer all seven ​questions? b. How many

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Question 1065512: Assume that you are taking a

seven
​-question
true or false quiz.
a.

How many different ways are there to answer all seven

​questions?
b.

How many ways are there to get no questions​ wrong? One​ question? Two​ questions?
c.

​If, not having​ studied, you simply guess at each​ answer, what are your chances of getting five

or more​ correct?

Answer by math_helper(2461)   (Show Source): You can put this solution on YOUR website!
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
ways to answer all seven questions.

b) To get no questions wrong: there is only way for that to happen.
To get one question wrong: there are ways for that to happen.
To get two questions wrong: there are 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

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