Logic Puzzles

[Dragoon Knight]

I can't remember seeing a topic along these lines in all my time here at FED2k, which means either my memory sucks, or it's high time that there was one. :P

Basically, this is a place to post Logic Puzzles; theoretical situations that challenge you to think, often "outside the box".  I really enjoy these things, and hopefully so will a lot of people here.  If there was a topic about this before, feel free to keep it to yourself and nick puzzles from the old thread without telling anyone / use it for getting answers to riddles. :P

If you know the answer to a riddle, please either PM me for confirmation, or use the HIDE brackets, so that you don't spoil it for others. :)

I'll start the thread off with a relatively simple one that requires some lateral thinking.

---

You are alone in a room with three switches, all of them set to "OFF".  One of these switches controls a lamp in a nearby room, and you need to find out which one it is.  None of these switches controls the light for the room you are in.

There is no way of seeing the lamp, or the light it emits, from the room you are in.  You may flip the switches as many times as you like, and take as long as you like.  You may leave the room once to look at the lamp, but when you return, you must know which switch controls the lamp.

You may not move the lamp or the switches, and all wiring is hidden from view.

How would you find out which switch controls the lamp?.

Have fun. :)

[Andrew]

Emprworm's Riddles

Were the best things ever.

Don't forget to use the hide tags for your answers!

[hide]Get someone to go in the other room and tell you if it is on[/hide]

:-

[Dragoon Knight]

Andrew:

[hide]Good guess, but not the right answer, I'm afraid.  You're totally alone in this riddle; I'll edit the original.  Keep trying; it took me a while as well. :)[/hide]

[gryphon]

Easy. . . uni riddle.. ..

[hide]turn over 2 of the switches, and waith for a couple of minutes. Then turn one swithch back off. Walk in the other room. If the lamp is still burning it's the switch that's still on. If it's of and the light bulb is still hot it's the one you just switched off. If the light bulb is cold it's the switch you never toutched[/hide]

[Dragoon Knight]

Gryphon:

[hide]Correct!  Now you post one. :P[/hide]

[Mihail]

Okay, lets see. Not really sure about this, though it should work. I remember I heard this one somewhere.

[hide]

Turn on two switches. Then wait for some time(You'll see where I'm going with this in a second). Turn one switch back off, then go into the other room. If the the light is still burning,  it is the one switch you left on. If the light bulb is hot but off, it is the switch you just turned off. If the light bulb is off and cold, it is the switch that you didn't turn on. :)

I think...[/hide]

Argh! Damn you for all eternity, gryphon! It seems you have beaten me to it. Well, that's what happens when you have an internet that is fast, but turns off at the most crucial times. :P

[gryphon]

;) To lighten your burden . . I'll pass my turn over to you :)

[Mihail]

Yaaaay! :D Here we go.

Nine cards are disposed as shown:

          +---+---+---+

          | a | b | c |

          +---+---+---+

          | d | e | f |

          +---+---+---+

          | g | h | i |

          +---+---+---+

1) There are, at least, two Aces, two Kings, two Queens and two Jacks.

2) Every Ace borders a King and a Queen.

3) Every King borders a Queen and a Jack.

4) Every Queen borders a Jack.

Note: "border" means "touch" horizontally or vertically, not diagonally.

By the way, this is a long one. I finally broke and had to check the solution because I couldn't figure it out. :P

Also, here is a fun quick one:

Don't cheat! Because if you did, the test would be no fun.I promise, there are no tricks to the test.

Read the sentence below and count the F's in that sentence.Count them ONLY ONCE. Do not go back and count them again.

See solutions for your score.

FINISHED FILES ARE THE RE-

SULT OF YEARS OF SCIENTIF-

IC STUDY COMBINED WITH

THE EXPERIENCE OF YEARS.

[hide]There are six F's in the sentence.

A person of average intelligence finds three of them.

If you spotted four, you're above average.

If you got five, you can turn your nose at most anybody.

If you caught six, you are a genius.

There is no catch.

Many people forget the "OF"'s.

The human brain tends to see them as V's and not F's.[/hide]

[Mihail]

Correct! Now you post one. :)

[erjin999]

And thats why I will never get one of those right. I cant think of any of my own to post in reply !

[Lord J]

Interesting!

[hide]I got the same answer as Spectral, just sideways :D !

a=Ace

b=King

c=Queen

d=Queen

e=Jack

f=Jack

g=Ace

h=King

i=Queen

Also, I used a post-it note to solve, is that prohibited?  It took me about 5 minutes. [/hide]

[Mihail]

Also, I used a post-it note to solve, is that prohibited?  It took me about 5 minutes.

Of course not! Solve it any way you like, just solve it right.If Spectral Paladin doesn't post one,then you can. :)

[Lord J]

Sorry, the best I can come up with comes out of my Psychology textbook.

:) :) :) Three Hobbits,

>:( >:( >:( Three Orcs,

And a Boat

  Although Orcs and Hobbits normally don't get along, the six are stationed, together, on one side of a river.  They all have to get across to the other side of the river.  Now, although the Hobbits pose no threat to the Orcs, the Orcs will eat the Hobbits if there are more Orcs than Hobbits on one side of the river.  The boat only holds two, but both races can be trusted to bring the boat back to the other side of the river.

Sorry, but that's the best I can come up with.

Please don't post with smiley faces in your answer, as they tend to show up in the Hidden Text boxes.  Thanks.

[gunner154]

[hide]Let's call the starting side Side A, while the destination is Side B. An orc will be the boatman (or boatorc, whatever you like to call it), and ferry an orc to Side B. Then go back to Side A and pick up a hobbit and send the hobbit to Side B. So Side B now has a hobbit and an orc while Side A has 2 hobbits and an orc (the last orc being on the boat). Have the boatman ferry a hobbit to Side B, so now Side B has 2 hobbits and an orc, while Side A has a hobbit and an orc. Have the boatman take the last hobbit from Side A to Side B, so now Side A has only one orc while Side B has 3 hobbits and one orc (hobbits don't kill orcs when they outnumber them right?). Now have the boatman go back to side A and get the last orc and bring him back, and then both get off the boat. All are across the river. [/hide]

[Lord J]

Close :)

[hide]  But would the Orcish boatman not join forces with the Orc on Side B and eat the Hobbit when he brought him across?  Try again :) [/hide]

[gunner154]

You mean being the boatman still counts? Pfft.

[hide]Have an orc ferry another orc to Side B, then the orc returns. Then the orc ferries another orc over to side B, so now there are 3 orcs on side B and 3 hobbits at side A. Then the orc returns and stays at side A while 2 hobbits go off to Side B. So there are 2 hobbits and 2 orcs at side B while only 1 hobbit and 1 orc at side A. Then have a hobbit and an orc return to side A, and then have both hobbits take the boat back to side B. Now all 3 hobbits are at side B while 1 orc is at side B and 2 other orcs at side A. Now the orc at side B can go to and fro to send the remaining orcs over to side B.[/hide]

I hope it's correct now. That was fun 8)

Edited: Just to clarify the answer a bit.

[Lord J]

Perfect :D.  Now you get to post one :)

[gunner154]

I'm taking mine off from some school discussion, but I don't have the answer to it. Can I still post it? ;)

Edit: Nevermind. I shall just post it and leave it to you guys to figure it out (I haven't found time to think this over yet, though it seems you don't really need to think about anything here..)

Protagoras