Who is the Spy?

Logic Level 2

You are the king of a castle, One of your servants told you that one subject is a spy. You then test everyone in your kingdom and are left with 3 people. Johnny, Brian, and Jesus. You know that the spy can tell a truth or lie and that the knight always tells the truth, and last, the knave always lies. - Johnny said, "Brian is the Spy!" - Brian said, "Jesus is the Knave!" - Jesus said, "I am the Spy!" Then you realize who is the knave spy and knight . Who is The spy?

Johnny None of them are Spy Jesus Not Enough Information Brian

Josue Manzo by josue manzo , 21, USA

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Agent T
May 10, 2021

Ig I'm the most capable person to answer this ques 😅 so let's get started,

Case 1: Johnny is the knight

  • = > Brian is the spy =>\text{Brian is the spy}
  • = > Jesus is the knave =>\text{Jesus is the knave}

Conclusion:Brian is the spy

Case 2:Brian is the knight

  • = > Jesus is the knave =>\text{Jesus is the knave}
  • = > Johnny is the spy =>\text{Johnny is the spy} Conclusion:Johnny is the spy

Case 3: Jesus is the knight

= > Jesus is the spy =>\text{Jesus is the spy}

this is a Contradiction \textcolor{#D61F06}{\text{this is a Contradiction}} !!! So Jesus is not the knight!

= > => Both Johnny and Brian have equal chances of being a spy but there's not enough info. for choosing any one of them.

Hence option d \boxed{\large{d}} is correct!

Boom!

0 Helpful 0 Interesting 0 Brilliant 0 Confused
Josue Manzo
Jan 29, 2018

This is well to easy. Johnny said, "Brian is the spy!" Brian said, "Jesus is the knave!" Jesus said, "I am the spy!" Brian=B Johnny=Jo Jesus=Je Jo said B is the spy. B said Je is the knave. Je said I am the spy.

If B was right, Je would be the knave, so he could not be the spy. B must have been the knight, but also can be the spy. Jo said B is the spy, so Jo must be the Knight and B the spy! Witch meant Jo=Knight, B=Spy, and Je=Knave!

0 Helpful 0 Interesting 0 Brilliant 1 Confused

Why can't Johnny be the spy (telling a lie), Brian the knight and Jesus the knave? It seems that the correct answer should be "Not enough information"

By the way, who is the witch?

Zee Ell - 3 years, 4 months ago

Johnny : Brian is the spy.
Brian : Jesus is the knave.
Jesus : I am the spy.

Jesus admits to being a spy, and that's not something a knight can do. So there must be a knight between Johnny and Brian.

Brian and Jesus are saying two different things, while Jesus and Johnny also aren't exactly agreeing to the other's statement. Therefore, we have on our hands a truthful spy Jesus with 2 lying others, OR a lying Jesus with at least one truthful others. The former case is moot since it's impossible for a Knight to be one of the 2 lying others, thus we must have a knave Jesus (since he must be lying and he cannot be a Spy anymore) and the other two to be either a Knight or a Spy.

Brian's statement is now a confirmed truth, so he could have been either a Knight or a Truthful Spy, but on the other hand, Johnny also could have been either a Lying Spy or a Knight respectively.

In conclusion, there's not enough information to determine who the Spy is between Johnny and Brian, but Jesus is still a knave either way.

Saya Suka - 4 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...