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46 replies to this topic

#31 Nabtalkin

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Posted 14 February 2008 - 03:56 AM

Im in algebra 2 so if X = weight of the the brick the equation would be X=1kg+1/2 x
Combine like terms using properties of equality if nessesary (subtaction property) X-1/2x=1kg+1/2x-1/2x
Simplify (Substatution property) 1/2x=1kg
Isolate variable 2*1/2x=1kg*2
SImplify x=2kg
Answer the question The brick weighs 2 kg

the weight has already been found so there is no need for any other formulas to solve the equation like the newtons thing and KG is a valid form of weight mesurment. That arguement is for another thread though

Edited by Nabtalkin, 14 February 2008 - 03:58 AM.

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#32 ITmIKE

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Posted 29 February 2008 - 10:02 PM

Just thinking about the result after reading a lot of posts. Another way to think about the problem... purely using logic and not relying on math equations.

The brick's total weight = 1kg + another 1/2 a brick. By this logic that means the other half of the brick must be the 1kg.. as there are no other weights in the problem.

So if by process of elimination of weights 1kg has to = 1/2 a brick weight. Therefore 1 brick HAS to equal 2kg.
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#33 heatherlovesjade

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Posted 04 March 2008 - 12:55 AM

1 1/2 kilograms
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#34 Zaedra

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Posted 05 March 2008 - 11:35 PM

well,
1 brick = 1kg + 1/2 brick

how heavy is 1/2 a brick?
1/2 brick = 1/2kg + 1/4 brick

how heavy is 1/4 brick?
1/4 brick = 1/4kg + 1/8 brick

etc. etc. etc...

so basically it becomes: 1 Brick = 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 +...+ and so on

[b]Conclusion[/b]
even though when u solve for the equation you get: (brick = x)
x = 1 + 1/2x
x - 1/2x = 1
x(1-1/2) = 1
x = 1 / (1 - 1/2)
x = 2

the real weight of 1 brick never really reaches 2. Instead, its
1.99999 > 2
(you can add as many 9s as u want...)
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#35 heatherlovesjade

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Posted 06 March 2008 - 02:49 AM

i get it now- x=1+1/2(x)
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#36 PolishNorbi

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Posted 07 April 2008 - 06:44 PM

well,
1 brick = 1kg + 1/2 brick

how heavy is 1/2 a brick?
1/2 brick = 1/2kg + 1/4 brick

how heavy is 1/4 brick?
1/4 brick = 1/4kg + 1/8 brick

etc. etc. etc...

so basically it becomes: 1 Brick = 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 +...+ and so on

[b]Conclusion[/b]
even though when u solve for the equation you get: (brick = x)
x = 1 + 1/2x
x - 1/2x = 1
x(1-1/2) = 1
x = 1 / (1 - 1/2)
x = 2

the real weight of 1 brick never really reaches 2. Instead, its
1.99999 > 2
(you can add as many 9s as u want...)


However, repeating 9999s after a decimal point = 1.
Simple proof,
.999 = x
10x = 9.9999999...
- x = .99999...
------------------------
9x = 9
x = 1
thus .999999... = 1
thus 2 is the correct answer
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#37 blondeclaire

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Posted 18 April 2008 - 02:42 PM

Call me dumb but i read it as

1 brick = 1.5kg

Can sum1 show me an EASY WAY to solve this? x
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#38 mythicallady636

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Posted 01 May 2008 - 06:24 AM

Ok this is an elementary problem not college.
In college you would take apart the wording to make sure you did not misunderstand.
it said that a brick(1 brick) weights 1 Kg then that 1/2 a brick is heavy before asking the weight of the brick.
It is one of those riddles that it gave you the answer in the beginning then handed you more filler information so that when it asked you to regurgitate the information back to it you are so confused you cannot answer properly.

the answer is 1 kilogram
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#39 bobbyalex

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Posted 04 May 2008 - 09:17 AM

guys, this problem doesn't need to be so complicated. the wording may be funny, but the solution is all the same:

first of all, a brick = one brick. what reason is there to distinguish the two?

secondly, let 1 brick = n

n = 1 kg + 1/2n
n - 1/2n = 1
anything minus half of itself equals the other half,
therefore: 1/2n = 1
n = 1 : 1/2 = 1 x 2/1 = 2
n = 2 kg
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#40 theshredder157

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Posted 04 May 2008 - 12:25 PM

ok guys, 1 brick = 1kg + 1/2 brick

so the 1kg is the only 1/2 if the brick

so that means that the other half also = 1kg


1kg+1kg=2kg

Edited by theshredder157, 04 May 2008 - 12:27 PM.

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