A multiple-choice quiz
by qrayx.
Estimated time: 24 mins.

Quiz Answer Key and Fun Facts

Answer:
**The blue knight**

This is often called the Three Knights problem. The classic responses have been tweaked to not make this question an exact copy.

Starting with the final statement, the green knight cannot be the Knight of Life. If asked who they were, the Knight of Life would have to tell the truth, saying they are the Knight of Life. So the red or blue knight must be the Knight of Life.

The Knight of Life would never say a different knight was the Knight of Life, but that's what the red knight did.

The only option left is the blue knight.

The blue knight is the Knight of Life, and told you the green knight is the Knight of the Dungeon, which means the green knight lied when he said he was the Knight of Death. The red knight must then be the Knight of Death, who lied when she said the green knight was the Knight of Life.

This is often called the Three Knights problem. The classic responses have been tweaked to not make this question an exact copy.

Starting with the final statement, the green knight cannot be the Knight of Life. If asked who they were, the Knight of Life would have to tell the truth, saying they are the Knight of Life. So the red or blue knight must be the Knight of Life.

The Knight of Life would never say a different knight was the Knight of Life, but that's what the red knight did.

The only option left is the blue knight.

The blue knight is the Knight of Life, and told you the green knight is the Knight of the Dungeon, which means the green knight lied when he said he was the Knight of Death. The red knight must then be the Knight of Death, who lied when she said the green knight was the Knight of Life.

Answer:
**Bob and Carl**

Starting with the first statement, we know that Alice and Bob are different (one is a truth-teller, and one is a liar). If they were both truth-tellers, then Alice's statement would be a lie (a contradiction). If they were both liars, then Alice's statement would be the truth (also a contradiction).

From Bob's statement, we know that he is a truth-teller, along with Carl, or he is a liar, and only Alice is a truth-teller. So Bob and Carl must be the same type, which means Carl and Alice must also be opposite types.

When Carl claims he and Alice are the same type, we know he is a liar. Thus, Carl and Bob are both liars, and Alice told the truth.

Starting with the first statement, we know that Alice and Bob are different (one is a truth-teller, and one is a liar). If they were both truth-tellers, then Alice's statement would be a lie (a contradiction). If they were both liars, then Alice's statement would be the truth (also a contradiction).

From Bob's statement, we know that he is a truth-teller, along with Carl, or he is a liar, and only Alice is a truth-teller. So Bob and Carl must be the same type, which means Carl and Alice must also be opposite types.

When Carl claims he and Alice are the same type, we know he is a liar. Thus, Carl and Bob are both liars, and Alice told the truth.

Answer:
**None of them**

The first statement means Dianne cannot be the only truth-teller, or the only liar.

The second statement means that either all three people are truth-tellers, or they are all liars, or Felicia is the only truth-teller.

We look at all three states with Felicia's statement in mind. If all three were liars, then Felicia's statement would be true (a contradiction). If Felicia was the only truth-teller, then her statement would also false (another contradiction). The only state with no contradictions is when all three people are truth-tellers.

The first statement means Dianne cannot be the only truth-teller, or the only liar.

The second statement means that either all three people are truth-tellers, or they are all liars, or Felicia is the only truth-teller.

We look at all three states with Felicia's statement in mind. If all three were liars, then Felicia's statement would be true (a contradiction). If Felicia was the only truth-teller, then her statement would also false (another contradiction). The only state with no contradictions is when all three people are truth-tellers.

Answer:
**Only Heather**

Before considering any statements, we'll acknowledge four possible states: Greg is the only truth-teller, Heather is the only truth-teller, they are both truth-tellers, or they are both liars.

Greg's statement does not allow for him to be a liar and for Heather to be a truth-teller (he'd be telling the truth, which is a contradiction). So we're only concerned with the three remaining states, and will consider Heather's response.

If they were both liars, then Heather would have responded, "Yes."

If they were both truth-tellers, then Heather would have responded, "Yes."

Lastly, if only Heather was a liar, then she would have said, "No."

Because the last state has a unique answer, when Sleuth knew for certain, so did we.

Before considering any statements, we'll acknowledge four possible states: Greg is the only truth-teller, Heather is the only truth-teller, they are both truth-tellers, or they are both liars.

Greg's statement does not allow for him to be a liar and for Heather to be a truth-teller (he'd be telling the truth, which is a contradiction). So we're only concerned with the three remaining states, and will consider Heather's response.

If they were both liars, then Heather would have responded, "Yes."

If they were both truth-tellers, then Heather would have responded, "Yes."

Lastly, if only Heather was a liar, then she would have said, "No."

Because the last state has a unique answer, when Sleuth knew for certain, so did we.

Answer:
**Isaac and Keith**

From the first statement we know that Isaac is either the only truth-teller, or at least one of the other two is a truth-teller. They cannot all be liars.

Jessica's statement means that she and Isaac are different types (one is a liar, and one is a truth-teller).

We now have three possible states: Isaac is the only truth-teller, Jessica is the only truth-teller, or Jessica and Keith are both truth-tellers.

We'll consider the possible responses Keith gave to these states:

If Isaac was the only truth-teller, then Keith would have said, "Yes."

If Jessica was the only truth-teller, then Keith would have said, "No."

If Jessica and Keith were both telling the truth, then he would have said, "Yes."

Again, only one state had a unique answer, which is how Sleuth was able to be certain after hearing Keith's answer.

From the first statement we know that Isaac is either the only truth-teller, or at least one of the other two is a truth-teller. They cannot all be liars.

Jessica's statement means that she and Isaac are different types (one is a liar, and one is a truth-teller).

We now have three possible states: Isaac is the only truth-teller, Jessica is the only truth-teller, or Jessica and Keith are both truth-tellers.

We'll consider the possible responses Keith gave to these states:

If Isaac was the only truth-teller, then Keith would have said, "Yes."

If Jessica was the only truth-teller, then Keith would have said, "No."

If Jessica and Keith were both telling the truth, then he would have said, "Yes."

Again, only one state had a unique answer, which is how Sleuth was able to be certain after hearing Keith's answer.

Answer:
**Naomi**

You actually only need one statement: Mike's.

Mike said Naomi was innocent, but you know he's a liar, which means Naomi is guilty.

Because only one person is guilty, the other two statements can also be verified as lies.

You actually only need one statement: Mike's.

Mike said Naomi was innocent, but you know he's a liar, which means Naomi is guilty.

Because only one person is guilty, the other two statements can also be verified as lies.

Answer:
**Penny**

From the first statement, we can tell that Oscar is either telling the truth and innocent, or is guilty and lying (not a great revelation when dealing with crooks).

Penny makes a similar statement, and we can draw a similar conclusion.

These two statements together, though, do something interesting: Quentin cannot be telling the truth. If Oscar was guilty, then Penny would be telling the truth. If Penny was guilty, then Oscar would be telling the truth. If Quentin was guilty, then both Oscar and Penny would be telling the truth (a contradiction, because there is only one truth-teller here).

So, knowing that Quentin is a liar, when he claims Oscar is guilty, we know that Oscar is actually innocent and the sole truth-teller. Therefore Penny must be a liar and the real culprit.

From the first statement, we can tell that Oscar is either telling the truth and innocent, or is guilty and lying (not a great revelation when dealing with crooks).

Penny makes a similar statement, and we can draw a similar conclusion.

These two statements together, though, do something interesting: Quentin cannot be telling the truth. If Oscar was guilty, then Penny would be telling the truth. If Penny was guilty, then Oscar would be telling the truth. If Quentin was guilty, then both Oscar and Penny would be telling the truth (a contradiction, because there is only one truth-teller here).

So, knowing that Quentin is a liar, when he claims Oscar is guilty, we know that Oscar is actually innocent and the sole truth-teller. Therefore Penny must be a liar and the real culprit.

Answer:
**Ruby**

Samson and Tiffany are saying the same thing (that Tiffany is guilty), but only one person can be telling the truth. This means they are both liars, and Tiffany is actually innocent.

Ruby must be the truth-teller, and she said Samson was innocent. Unfortunately for her, that leaves Ruby herself as the only possible criminal.

Samson and Tiffany are saying the same thing (that Tiffany is guilty), but only one person can be telling the truth. This means they are both liars, and Tiffany is actually innocent.

Ruby must be the truth-teller, and she said Samson was innocent. Unfortunately for her, that leaves Ruby herself as the only possible criminal.

Answer:
**Vivian**

Ulysses' statement actually makes things quite easy for us. Either he is the truth-teller, or Vivian is guilty.

Vivian then goes on to accuse Wallace or Xena of committing the crime. Unfortunately, if Wallace or Xena committed the crime, that would make both Vivian and Ulysses truth-tellers (which is not allowed).

The only possible states now are that Ulysses is telling the truth and that he is guilty, or that Vivian is guilty, and one of the other two is telling the truth.

Wallace then says Ulysses is guilty. If Ulysses was guilty, then both he and Wallace would be truth-tellers (again, not allowed), so Wallace is a liar.

The only possible solution now is that Vivian is guilty, and Xena is the only truth-teller (despite not having to say anything at all).

Ulysses' statement actually makes things quite easy for us. Either he is the truth-teller, or Vivian is guilty.

Vivian then goes on to accuse Wallace or Xena of committing the crime. Unfortunately, if Wallace or Xena committed the crime, that would make both Vivian and Ulysses truth-tellers (which is not allowed).

The only possible states now are that Ulysses is telling the truth and that he is guilty, or that Vivian is guilty, and one of the other two is telling the truth.

Wallace then says Ulysses is guilty. If Ulysses was guilty, then both he and Wallace would be truth-tellers (again, not allowed), so Wallace is a liar.

The only possible solution now is that Vivian is guilty, and Xena is the only truth-teller (despite not having to say anything at all).

Answer:
**Yvonne**

Similar to the previous question, we're going to let the second statement do a lot of work for us. Either Zadie is telling the truth, or Britney is guilty.

Next, Yvonne's statement. If Zadie was guilty, then both Yvonne and Zadie would be telling the truth, which is a contradiction. Yvonne cannot be a truth-teller, which means Zadie is definitely innocent. We still don't know if Zadie is telling the truth or not.

Some quick accounting shows us the remaining possible states:

- Zadie is telling the truth, and either Yvonne or Aaron is guilty.

- Britney is guilty, and either she or Aaron is telling the truth.

Aaron claims that Yvonne and Britney are both innocent, so either he's telling the truth, or one of them committed the crime. We've halved our number of possible states, down to two:

- Zadie is telling the truth and Yvonne is guilty

- Britney is guilty and telling the truth

Finally, Britney claims that Aaron is guilty, which means she cannot be telling the truth. Zadie must be telling the truth, and Yvonne must be guilty.

Similar to the previous question, we're going to let the second statement do a lot of work for us. Either Zadie is telling the truth, or Britney is guilty.

Next, Yvonne's statement. If Zadie was guilty, then both Yvonne and Zadie would be telling the truth, which is a contradiction. Yvonne cannot be a truth-teller, which means Zadie is definitely innocent. We still don't know if Zadie is telling the truth or not.

Some quick accounting shows us the remaining possible states:

- Zadie is telling the truth, and either Yvonne or Aaron is guilty.

- Britney is guilty, and either she or Aaron is telling the truth.

Aaron claims that Yvonne and Britney are both innocent, so either he's telling the truth, or one of them committed the crime. We've halved our number of possible states, down to two:

- Zadie is telling the truth and Yvonne is guilty

- Britney is guilty and telling the truth

Finally, Britney claims that Aaron is guilty, which means she cannot be telling the truth. Zadie must be telling the truth, and Yvonne must be guilty.

This quiz was reviewed by FunTrivia editor Fifiona81 before going online.

Any errors found in FunTrivia content are routinely corrected through our feedback system.

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