A logic problem by Skand Singh
Logic
Level
3
If you have 9 sacks all are identical and equal in weight except one, which may be either lesser or more than remaining 8 sacks. You have an ELECTRONIC SCALE. How many minimum times will you weigh to find out the defected sack?
4
3
1
2
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1 solution
Let suppose every sack is of weight "10 kg" and the defective one is of "8kg". Let's put the first sack on the Electronic Scale, if it reads "8" this means the first sack is the defective one but if it read "10" this means the sack is not defective. Now put another sack without replacing the first one, now the scale will either read "18" or "20" if it reads "18" this means 2nd sack is defective but if it reads "20" this means 2nd sack is also not defective. Repeat this process till last, every time you'll get a multiple of 10, but when you see the reading is not up to the mark then it's crystal clear that the current sack is the defective one. THE main catch in this question is, we're using ELECTRONIC SCALE, we're not replacing sacks, instead we're putting on and on, so, this will be counted as 1 time.