IQ Brain Teaser #72
Using a balancing weight scale with 2 pans similar to the type shown below, what is the minimum number of weights (each being in 1 pound increments, so you could have 2 one pound weights, 1 three pound weight, etc.) you would need to bring into balance individual objects (not more than 1 of these objects is in your possession at any given time) that weigh anywhere from 1 to 25 pounds, in 1 pound increments? Which weights would you need (i.e. how many 1 pound weights, 2 pound weights, etc.)?



2 weights: 7 pound and 11 pound
2 weights: 5 pound and 17 pound
3 weights: 3 pound, 7 pound and 13 pound
3 weights: 2 pound, 7 pound and 13 pound
3 weights: 2 pound, 5 pound and 15 pound
3 weights: 1 pound, 7 pound and 15 pound
3 weights: 1 pound, 8 pound and 15 pound
3 weights: 3 pound, 7 pound and 15 pound
4 weights: 1 pound, 3 pound, 9 pound and 27 pound
None of the above will work

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