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# A few problems

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Here are a few problems for you; they are not extremely hard to solve, but it may take a few time anyway to resolve them.

Problem number 1: Imagine you are given two barrels, one with a capacity of 5 L, and the other with a capacity of 3 L.

Given that the barrels ain't graduated, can you manage to put exactly 4 L in the largest barrel?

N.B.: You may completely fill and empty the two barrels as many times as you want, and decant the content of one in the other.

Problem number 2: A thiefs breaks into a museum and steals nine jewels; but he knows that only one of them is a real one, the eight other ones being fake. He only knows that the real jewel is slightly heavier than the others, but he only has a Roberval balance, meaning he can't get the exact masses of the jewels.

In only two weighings, can he find the real one?

Problem number 3: What is thirty divided by a half plus twenty?

Problem number 4: With six identical matches, can you make exactly four triangles?

Good luck!

N.B.: I think marking the work is useless, so I won't mark these questions. Anyway, if you get them all right, you still earn a brownie!

Feb 5, 2016

#5
+15

#1   Fill 5    then fill 3 from it  leaving two in 5      dump 3   and puor the reaming two into it       Fill five again then pour from it to fill 3 (it will only take one gallon since it already has two in it)...that will leave 4 gal in the 5 gal barrel

Feb 5, 2016

#1
+8574
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I want.. a.. Brownie....

Feb 5, 2016
#2
+8574
+15

3.

30/ 1/2 + 20

80! :)

Feb 5, 2016
#3
+870
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Good, you got the answer to one question; three to go!

Feb 5, 2016
#4
+8574
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Ugh. XD

Feb 5, 2016
#5
+15

#1   Fill 5    then fill 3 from it  leaving two in 5      dump 3   and puor the reaming two into it       Fill five again then pour from it to fill 3 (it will only take one gallon since it already has two in it)...that will leave 4 gal in the 5 gal barrel

Guest Feb 5, 2016
#6
+870
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That's correct Guest!

Since I think there won't be one person who answer all four questions, I'll give a cookie to everyone who has reolved one or more of the problems when the four are solved.

Feb 5, 2016
#7
+111325
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Problem 2

Put 3 jewels on one side and 3 on the other :

1st scenario - they balance

Take them all off

Pick any two of the remaining three jewels

Put them on the scale.....if they balance....the remaining one is the real one

If they don't balance......the real one has to be the heavier

Result......real one is found after just two weighings

2nd scenario - they don't balance and one side is heavier

Take the three jewels from the heavier side

Pick any two of these

Put them on the scale.....if they balance....the remaining one is the real one

If they don't balance......the real one has to be the heavier

Result......real one is found after just two weighings

Feb 6, 2016
#8
+5266
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Lets see... You said only using six matchsticks. You never said I couldn't break them apart! e.e Break the matchsticks until you have 12 pieces and make 4 triangles.

Feb 8, 2016
#9
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I don't  think that that is alowed rarinstraw LOL

Feb 8, 2016
#10
+870
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Melody, you're right, breaking the matches isn't allowed (but 3D is allowed; I just gave you all a huge hint!)

Feb 16, 2016
#11
+5266
+5

#4, make a triangular pyramid.

Feb 16, 2016
#12
+5266
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Brownie nao?

rarinstraw1195  Feb 16, 2016
#13
+870
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That's right rarinstraw1195; here is a triangular pyramid (or a tetrahedron; let's call a spade a spade):

Congratulations to Hayley1, Guest, CPhill and rarinstraw1195 for solving those problems; you each deserve a brownie!

Yum...

Feb 17, 2016