Ruzzle/Riddle Thread

There are 2 containers one holds 7 liters and one holds 5 liters. you need 4 liters of water. how can you measure it using only these 2 containers?
 
Fill the 7 liter container. Use the full 7 liter container to fill the 5 liter container. Empty
the remaining 2 liters left in the 7 liter container into your 3rd container. Repeat after emptying the 5 liter container. You
did not state there were a total of two containers, only that those two could be used for
measuring the 4 liters.
 
Fill 7-liter container. Take away 5-liter using the other container. Empty the 5-liter one.
Pour the 2 remaining to the 5-liter.
Fill 7-liter container. Pour until 5-liter container is full. 4-liter is left in 7-liter container.
 
Wasn't this in one of the Die Hard movies?

Lol we need more riddles and ruzzles I like this thread. Too bad melodicbard beat me to the punch. :rolleyes:
 
Melodicbard correct (only two containers are allowed)

Next puzzle:

In a certain bulding, there are switches numbered from 1 to 100 that are currently in the "on" position. Betty, the caretaker, starts switching the switches to the "off" position, starting with the multiples of 1. She then goes back and swittches all of the switches numbered with an multiple of 2 to the opossite direction, and then switches all of the multipples of 3 in the opposite direction again, and continues to do so until she comes to the multiples of 100. How many switches are now in the "off" position?
 
When you say "multiples" does that mean the base number as well? ie when she switches the '2's does she switch no. 2?
 
Base nr. are not included. (eg. nr. 2 is not included) Multiples well.
 
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ProCop said:
Melodicbard correct (only two containers are allowed)

Next puzzle:

In a certain bulding, there are switches numbered from 1 to 100 that are currently in the "on" position. Betty, the caretaker, starts switching the switches to the "off" position, starting with the multiples of 1. She then goes back and swittches all of the switches numbered with an multiple of 2 to the opossite direction, and then switches all of the multipples of 3 in the opposite direction again, and continues to do so until she comes to the multiples of 100. How many switches are now in the "off" position?
Click to expand...

90 switches will be "off".

All switches will be switched once for each of their factors, including 1, but not including themselves.
Since factors come in pairs, each switch will be switched an odd number of times... except if a pair of factors is the same number - square numbers!

So only square numbered switches (1, 4, 9, 16, 25, 36, 49, 64, 81, 100) will be switched an even number of times and end up in the "on" position. The other 90 will be switch an odd number and end up in the "off" position.
 
Pete - very good again.


---------------------------------------

Analogy:

Fill in/finish the analogy:
<b>H is to GRAM as D is to.... ?</b>

-----------------------------------------------------

Logic

A man asked the the shopkeeper in the hardware shop, "How much will one cost?" "Two euros" the shopkeeper replied. "And how much would twelve cost?" the man asked. "Four euros." the shopkeeper replied. "OK, I will then take one hundred and twelve" said the man.

How much did he have to pay?
 
Analogy answer: MITE - if you put OLO in between H and GRAM you get HOLOGRAM. Similarly with second set, you get DOLOMITE.

Logic answer: 6 euros (the man is buying house numbers, with the numbers 1 and 2 each costing 2 euros)

Here's one I heard today:
There are 100 coins on the table in front of you, 30 showing heads, 70 showing tails. You are blindfolded, and you now have to separate the coins into two piles, each pile having the same number of heads showing (you are allowed to flip the coins over).
 
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@geodesic
analogy: not correct/expected answer (though your solution is OK you got a filling usable for both parts, but there is a more elegant sollution)

coins, supposing that I can feel the difference between heads and tails (that they feel different, I would turn all coins one way (thus 100 coins heads or 100 tails up), then I make a pile of 50 and building the next file of fifty I'll turn the coins around. They will be 50 heads up and 50 tails up - though I wouldn't know which is which. Is it sufficient?
 
geodesic said:
Here's one I heard today:
There are 100 coins on the table in front of you, 30 showing heads, 70 showing tails. You are blindfolded, and you now have to separate the coins into two piles, each pile having the same number of heads showing (you are allowed to flip the coins over).
Click to expand...

This is a great puzzle, but I've heard it before. The puzzle is solvable without needing to be able to distinguish between heads and tails by touch, or in fact at all.

HINT: It's sort of related to the Water in the wine / wine in the water puzzle.
 
I've got it! The piles are then not 50-50 but in the ratio 70-30
if I take from 100 coins 30 heads (by accident) and <b> turn them</b> then I have none head in both piles.

if I take 29 heads and 1 tail and turn them than I have 1 head in both....and so on.

Wow, great puzzle!!

Thanks for the hint Pete :)
 
Okay, another riddle I heard today:
We have two spheres in thermal equilibrium, one standing on a thermally insulating plate, one suspended from a thermally insulating string. Each sphere is now heated by the same amount.
Are the spheres at the same temperature, and if not, which is hotter?
 
geodesic said:
Okay, another riddle I heard today:
We have two spheres in thermal equilibrium, one standing on a thermally insulating plate, one suspended from a thermally insulating string. Each sphere is now heated by the same amount.
Are the spheres at the same temperature, and if not, which is hotter?
Click to expand...


If the general surroundings is vacuum, then I would say the A B spheres differ only in the size of the contact space with the supporting elements (string, plate). There must be some movements of atoms which takes away the warmth from the sphere at the place of contact, therefore the sphere on the plate is colder.
 
If it was a perfect sphere, wouldn't only intersect the place at one point, as the string would only intersect at one point?

However, the thermal plate might radiate heat back onto the sphere, moreso than the string would....
 
Analogy:

Fill in/finish the analogy:
<b>H is to GRAM as D is to.... ?</b>
[/QUOTE]


Some valuable thinking shown again (Roman) but the sollution is at a different corner:

histogram distortion
 
ProCop, Roman: When I say thermally insulating, I mean perfectly thermally insulating.
 
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