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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
Q1. Which is the first question where c) is the correct answer
a) Q3 b) Q4 c) Q1 d) Q2
D
Q2. Which is the first question where a) is the correct answer
a) Q4 b) Q2 c) Q3 d) Q1
C
Q3. Which is the first question where d) is the correct answer
a) Q1 b) Q2 c) Q4 d) Q3
A
Q4. Which is the first question where b) is the correct answer
a) Q2 b) Q4 c) Q3 d) Q1
B
Andrew Smith has the correct answer, namely
1D, 2C, 3A, 4B,
but here's a full explanation.
Let's look first at Q2, since it's the only one that can't be self-referential (e.g. for Q3, the answer d) would be self-confirming). The answer to Q2) can't be a) since then it couldn't be a), or b) since then it must be a). Also 2d) implies 1a) implies 3c) implies 4d) implies 1b), contradiction. So the answer to Q2) is c). This immediately implies the answer to Q3) is a), which implies the answer to Q1) is d). None of the answers so far is b), so there's only one possible answer to Q4): the answer to Q4) is b).
QED.
