There is a room with 17 vaults, labelled 1 to 17. In each vault there
are 20 to 30 gold bars. All gold bars look exactly the same, but there
is a problem: one vault contains exclusively real gold bars, in the
rest of the vaults all bars are fake and worthless. The only
observable difference of the bars is the weight: The real gold bars
are 1050 grams, the fake gold bars are 1000 grams.

You can keep all the bars of one vault, so you want to know which one
contains the real gold bars.

Here's what you can do: 

(1) You may take out any number of fake or real gold bars out of any
of the vaults.

(2) You may weigh any combination of the bars on a scale (the scale
can easily detect gram differences in a range of 1 to 500 kg).
However: you may only weigh ONCE (1 times), meaning you may put all
the bars you want on the scale, read the weight the scale returns,
think for a while, and name the number of the vault containing the
real gold bars.

hai 
i am not yet a google researcher .
If the answer is satisfactory u can withdraw the question ...

======================================
In order to solve this puzzle, remember these hints:

    * We don't know how much the bags weigh, so don't put the bags on the scale.
    * In other words, you may open the bags
    * You don't have to put all the bars on the scale
    * Why don't you put ten different piles of gold bars on the scale?
    * Make sure each pile has a different number of bars in it.
    * Use your calculator to see how much all the bars on the scale
SHOULD weigh if all the bars are perfect.
    * How many ounces too heavy is the fake bar?
    * I bet you can finish it from here. 



http://www.mazes.com/scales/Scale203.html


Search Strategy used

fake weight puzzle "gold bars"


A term in quotes is taken as a phrase untouched by google.

Best regards
arun

Hai 

I am not yet a google researcher either ...

BUT, using sultanarun-ga's method, I cannot figure how he can possibly
get a fix on the real bars.

Got it!

Here's what to do:

Take 1 bar from Vault 1;

2 bars from Vault 2; etc.

Then weigh the lot.

From the total weight, you can then deduce the Vault Number from the excess weight!

Bingo!

probonopublico - you are absolutely correct. Kudos to you for your
exceptional logical thinking.
When you weigh all the bars according to probono's suggestion, you
will have a total between 159800 - 160600 grams. The following chart
will tell you which vault the REAL gold is in.

Weight  Vault
160600	1
160550	2
160500	3
160450	4
160400	5
160350	6
160300	7
160250	8
160200	9
160150	10
160100	11
160050	12
160000	13
159950	14
159900	15
159850	16
159800	17

Er, well not quite, flajason ...

You would weigh 153 bars with 152 @ 1000 and 1 @ 1050, etc. to give
the following table:

Weight  Vault

153050	1
153100	2
153150	3
153200	4
153250	5
153300	6
153350	7
153400	8
153450	9
153500	10
153550	11
153600	12
153650	13
153700	14
153750	15
153800	16
153850	17
	
	153

The total weight would increase consistent with the number of real (ie
heavier) bars.

My apologies. I transposed the weights...

Original question:
Fake gold = 1000g
Real gold = 1050g

In my reality:
Fake gold = 1050g
Real gold = 1000g

I probably did this subconsciously thinking that the fake gold would
have been made from lead, which is slightly heavier than gold.
Au=196.9, Pb=207.2