Riddle me this, Riddle me that!

Eugene said:
That's it. Your turn.
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Hopefully not as bad as the one from Friday... and If you get it this time Eugene, I'll make sure that you get due credit :D

In a factory, there are ten sacks of goods, each with ten goods weighing 1 kg each (total 10 kg). A worker tells the quality control person that one of the sacks is lighter than the others, filled with ten .9 kg items, totalling 9 kg, instead of the normal 10 kg sacks. The quality control man decided that he could find the lighter sack with only one weighing. How did he do this?
 
Put all 10 sacks on the scale and take them off one at a time until the weight becomes a multiple of 10. Then the last sack he took off is the 9kg sack. Not sure if that counts as one weighing though.
 
matt said:
Put all 10 sacks on the scale and take them off one at a time until the weight becomes a multiple of 10. Then the last sack he took off is the 9kg sack. Not sure if that counts as one weighing though.
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That would count as multiple weighs. One weigh is one observation of the scale.
 
StaggerLee said:
Hopefully not as bad as the one from Friday... and If you get it this time Eugene, I'll make sure that you get due credit :D

In a factory, there are ten sacks of goods, each with ten goods weighing 1 kg each (total 10 kg). A worker tells the quality control person that one of the sacks is lighter than the others, filled with ten .9 kg items, totalling 9 kg, instead of the normal 10 kg sacks. The quality control man decided that he could find the lighter sack with only one weighing. How did he do this?
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Is this one a little too difficult as well?
 
Perhaps the QC guy should ask the worker which sack is the 9kg sack, and just weigh that one to make sure
 
matt said:
Perhaps the QC guy should ask the worker which sack is the 9kg sack, and just weigh that one to make sure
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For the sake of the problem, I think it's safe to assume that the 9kg bag is a result of a logistical error and the worker just knows that there's an error but doesn't know where it is.
 
It says 10 sacks with 10 goods in. From looking sat the bag, you should be able to see which one looks different? Then weigh just that one? (if 10 x something = 10 kg and 10 x something = 9kg, surely the bags will look different?)
 
TBlaar said:
It says 10 sacks with 10 goods in. From looking sat the bag, you should be able to see which one looks different? Then weigh just that one? (if 10 x something = 10 kg and 10 x something = 9kg, surely the bags will look different?)
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Nope, they all look the same.

A clue: You have to use a specific method that involves removing items from the bags and weighing those.
 
If it counts as "one weighing", he can keep tossing bags on the scale, one at a time, until the total goes up by 9kg instead of a full 10kg.

Edit: decimal point
 
It has to be something like this:
- number the bags left to right
- take from each bag, the amount of items that the bag is numbered with
- weigh all the items you removed (ie, it will be less than the total amount added up, as one is lighter)
- subtract that from the total weight of all bags
- the answer will be a number, indicating which numbered bag contained the fewer items

It's the only weigh (:D) I see this to be doable?!?
 
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