Halloween Special – Aggro 2 Solution

Answer: Ask sister A “is sister B the younger of your two sisters?”
If she says yes, marry B. if she says no, marry C.

You know that you can’t count on the sister you ask the question to because she could be the middle child. So, start by not picking whomever you ask your question to, regardless of the answer they give.

You need to work out a question that will provide the same result no matter who you ask.
We’ll call them sister A, B and C. You’ll have the following options:

ABC
Honest (oldest)Fickle (middle)Liar (youngest)
Honest (oldest)Liar (youngest)Fickle (middle)
Fickle (middle)Honest (oldest)Liar (youngest)
Fickle (middle)Liar (youngest)Honest (oldest)
Liar (youngest)Honest (oldest)Fickle (middle)
Liar (youngest)Fickle (middle)Honest (oldest)

There are 6 possibilities in total. Because they all look the same, it does not matter who is A, B or C, so we will be focusing on A.

Now ask A: Is B the younger of your two sisters?

AA’s answerBC
Honest (oldest)NoFickle (middle)Liar (youngest)
Honest (oldest)YesLiar (youngest)Fickle (middle)
Fickle (middle)?Honest (oldest)Liar (youngest)
Fickle (middle)?Liar (youngest)Honest (oldest)
Liar (youngest)YesHonest (oldest)Fickle (middle)
Liar (youngest)NoFickle (middle)Honest (oldest)

If A says YES, you choose B. If A says NO, you choose C. The goal here is not to find out their identities – it’s to avoid Ms. Fickle. A (liar) and A (honest) both rule her out in the following way:

AA’s answerYou’ll marryBC
Honest (oldest)NoCFickle (middle)Liar (youngest)
Honest (oldest)YesBLiar (youngest)Fickle (middle)
Fickle (middle)??Honest (oldest)Liar (youngest)
Fickle (middle)??Liar (youngest)Honest (oldest)
Liar (youngest)YesBHonest (oldest)Fickle (middle)
Liar (youngest)NoCFickle (middle)Honest (oldest)

“Is sister B the younger of your two sisters?”

If A replies with YES, you marry B. You’ll get the lying sister if she’s honest, and the honest sister if she’s a liar.
If A replies with NO, you marry C. You’ll get the lying sister if she’s honest, and the honest sister if she’s a liar.
It does not matter what the fickle sister says, because you are not choosing her to begin with, so you’ll be safe no matter what!

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