Re: Tough brainteaser.
OK here goes!
1) Weigh AB vs CD. If they are equal A, B, C and D are normal and the outlier is either E, F, G or H. If they are unequal then outlier is A, B, C, or D and E, F, G, H are normal. So in effect we've narrowed the field down to 4.
2) Weigh 2 'normal' balls vs 2 'unknown balls' If they balance then the two unknown balls are normal. If they don't balance one the two weighed unknown balls is the outlier. Either way you norrow the field down to two unknowns.
3) Wiegh one of the two unknown balls aganst a normal ball. If they match then the outlier is the final (unwieghed) ball. If they dont match the outlier is the wieghed unknown ball.
I hope this makes sense
aquifex
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