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# Brick

## 47 posts in this topic

Posted · Report post

x=brick weight

x=1+1/2x

1/2x=1

x=2kg

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Posted · Report post

that is sssssssssssssooooooooooooooooooooooooooooooooooooooooooo stupid even my mom said so. netwebdave explanied it to me thanks

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Posted · Report post

A brick weighs 2 Kg + 1/2 a brick. Therefore, 1/2 brick + 1/2 brick = 2 Kg, so 1/2 a brick weighs 1 Kg.

Hence 3 half bricks must weigh 3 Kg.

Alien1

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Posted · Report post

Sorry people,

I was thinking in pounds, which would have been 3.3 pounds .

The answer should be one and one half Kg.

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Posted · Report post

This is my first visit to the site, and I've never posted before, but I found the discussion interesting and figured I'd throw my .02 in.

An old riddle is as follows: One brick is one kilogram and half a brick heavy. What is the weight of one brick (previously: How heavy is one brick)?

(This is a typical elementary math brain teaser.)

I think the intent of the riddle is weight = mass, so we can throw all the weight vs. mass debates out the window, it just complicates things.

If one follows the algebraic interpretation of this riddle, one would be inclined to assume that the equation would look like this:

1 brick = 1kg + .5 brick

or

1x = 1kg + .5x

so

1x - .5x = 1kg

.5x = 1 kg

x = 1kg/.5

x = 2kg

the 2 kg answer is correct, but the wording of the riddle is slightly flawed and open to interpretation. If we look at the problem as parsimoniously as possible, which is likely what the riddle-maker intended, it yields a logical answer of 1 brick = 2kg.

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Posted (edited) · Report post

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
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Posted · Report post

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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Posted · Report post

1 1/2 kilograms

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Posted · Report post

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

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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Posted · Report post

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

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Posted · Report post

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

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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Posted · Report post

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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Posted · Report post

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.

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Posted · Report post

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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Posted (edited) · Report post

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
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Posted · Report post

I guess this depends on how you read the question. I read (1 brick is 1 kg) and (1 brick is half a brick heavy), not (1 brick is (1kg + half a brick) heavy). It's the difference between me reading "and" as a logical operator and you reading "and" as an arithmetic operator. Under my version, there are two options:

1. The term "brick" is ambiguous. You just said "one brick" weighs* 1 kg, so how can it also weigh 2 kg? If "one brick" is typical of "a brick" then the word problem is invalid:

1 brick = 1/2 brick

1 brick = 1 kg

1 kg = 1/2 * 1 kg

1 kg = 1/2 kg

1 = 1/2

Since 1 does not equal 1/2, 1 brick does not equal 1/2 brick and the problem is invalid.

2. If "one brick" is not typical of "a brick", then the problem changes:

1 [one brick] = 1/2 [a brick]

1 [one brick] = 1 kg

1 kg = 1/2 [a brick]

2 kg = [a brick]

1 [one brick] = 1/2 [a brick]

1 kg = 1/2 * 2 kg

1 kg = 1 kg

1 = 1

Since 1 does equal 1, this version is accurate, "one brick" weighs 1 kg and "a brick" weighs 2 kg. However, the question is not how much "a brick" weighs, but how much "one brick" weighs, so no math is necessary: "one brick" weighs 1 kg, as stated, and the answer is 1 kg, not 2 kg. As I read it, it's a very simple logic problem designed to confuse by seeming more complicated than it is.

Under the other interpretation, your answer of 2 kg is valid, but it's not a logic problem anymore.

* Technically, kg measures mass, not weight. So a valid answer on Earth would either be 2.2 lbs (the weight of 1 kg sitting on the surface of Earth) or 4.4 lbs (2 kg), depending on which interpretation we went with. Since you said "how heavy", not "what is the weight", this may be an inaccurate semantic argument, but is something I came up with under the logic realm.

you really missed this one, I think you over-thought it LOL

your premise to begin is invalid: 1 brick = 1/2 brick

the problem stated" 1 brick = 1 kg + 1/2 brick

be careful on your assumptions and keep on trying!

otherwise your technical analysis is very well thought out

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Posted · Report post

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

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...)

Well it actually does as that 1.99999.... = 2

check it out:

let x=1.9repeated.

then 10x = 19.9repeated

subtract x = 1.9 from that and you get:

9x = 18

divide both by 9

x=2

Q.E.D.

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Posted · Report post

Wow, i cant believe there's so many responses to such an easy problem...

Ok ppl, I think the easiest way to go about solving this problem without any algebra or whatever else, is to simply use ur imagination. Sounds cheesy, but picture this:

Picture a balance, on one side is one brick and on the other side is half a brick PLUS a KG of whatever the heck u'd like to imagine.... (rocks in a bag, eggs, whatever)

Now, since the two sides must obviously balance out, since the problem stated this, you must know that the half-brick has to equal the kilo of whatever you have to balance with the other whole brick. Because its like having 2 halves of brick on one side and on the other the half brick plus something that weighs the SAME as half a brick (which is the 1kg). So the solution becomes very obvious once you picture that.

I do have to admit, it was a bit confusing at first with the way it was worded, but a little bit of thinking and.... it was a piece of cake

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Posted · Report post

1 brick equals 1 and 1 and a half kgs is the the answer because one brick =one kg and half a brick so half of a brick would be half a kg. right?

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Posted · Report post

Problems like this always frustrated me in school because Like many people posting answers here I am too smart. What I mean is this riddle is valid but stated but in an ambiguous manner. You would never state the question like the original poster did because you recognize it as ambiguous. If you assume that the person asking the riddle is also smart enough to recognize that its ambiguous you then assume there must be something your missing. What the riddle should teach you is not some new mathematical equation but rather to look at problems differently. Often in life you are dealing with people who will not recognize their own ambiguity. So try to relax and realize that the simplest answer is usually the right one. Although I admit my very first thought was 1 brick = 1 kilogram but then I reread it and realized 1 brick = 1 kilogram and(+) 1/2 a brick that is natural and I believe the intent of the riddle.

1 brick = 2 kilograms

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Posted · Report post

Brick - Back to the Logic Puzzles

One brick is one kilogram and half a brick heavy.

What is the weight of one brick?

Brick - solution

There is an easy equation which can help:

1 brick = 1 kg + 1/2 brick

And so 1 brick is 2 kg heavy.

An old riddle is as follows: One brick is one kilogram and half a brick heavy. What is the weight of one brick (previously: How heavy is one brick)?

(This is a typical elementary math brain teaser.)

I guess its a matter of perseption:

The statement says one brick is heavier by 1kg and the weight of one brick.

and the question is how much does 1 brick weight.

So if one brick is heavier than the other then the following is true:

1st we have 2 bricks

the first brick is of normal weight = X (unknown)

the second is also unknown lets call it Y

so: Y = X + (1kg + 1/2X)

it will be an equation not a solid number!

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Posted · Report post

I guess its a matter of perseption:

The statement says one brick is heavier by 1kg and the weight of one brick.

and the question is how much does 1 brick weight.

So if one brick is heavier than the other then the following is true:

1st we have 2 bricks

the first brick is of normal weight = X (unknown)

the second is also unknown lets call it Y

so: Y = X + (1kg + 1/2X)

it will be an equation not a solid number!

I think the weight is uniform for all bricks, so there is only 1 unknown (the weight of the brick), not 2

x = 1 + 1/2x

1/2x = 1

x = 2

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