Puzzle Details

BrainBashers Entry Exam Section D

Here is snippet of section D of the curious multiple-choice entrance exam into the exclusive BrainBashers puzzle club.

Q1. Which is the first question where c) is the correct answer?
a) Q3
b) Q4
c) Q1
d) Q2

Q2. Which is the first question where a) is the correct answer?

a) Q4
b) Q2
c) Q3
d) Q1

Q3. Which is the first question where d) is the correct answer?

a) Q1
b) Q2
c) Q4
d) Q3

Q4. Which is the first question where b) is the correct answer?

a) Q2
b) Q4
c) Q3
d) Q1

1. d)
2. c)
3. a)
4. b)

Looking at the questions, only Q2 has an answer that doesn't reference itself directly. For example Q1 asks about c) as an answer, but its answer c) is Q1.

So it's easiest to look at Q2 first.

Q2's answer can't be b) (as this would be an immediate contradiction), so Q4's answer can't be a), so Q2's answer can't be a).

Q2 can therefore be either c) or d).

If Q2's answer was d), then Q1's answer would be a), so Q3's answer would be c), so Q4's answer would be d), so Q1's answer would be b). However this now contradicts itself, so Q2's answer can't be d).

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