问一个称球的问题 (转载)# WaterWorld - 未名水世界
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【 以下文字转载自 Quant 讨论区 】
发信人: danmu (团团), 信区: Quant
标 题: 问一个称球的问题
发信站: BBS 未名空间站 (Mon Oct 25 09:42:57 2010, 美东)
You have nine balls, three of which are slightly heavier, and three of
which are slightly lighter than the normal three. All three balls in each
group have the same weight. All nine balls are identical otherwise. Your
mission is to determine the group of every ball using a pair of scales.
How many weighings are needed in order to ensure the accomplishment of
your mission?
Notes:
1. The difference of weight between the heavy and normal balls is not
necessarily equal to the difference of weight between the light and normal
balls.
2. The scales show only which side is heavier; it does not show the
difference of weight.
发信人: danmu (团团), 信区: Quant
标 题: 问一个称球的问题
发信站: BBS 未名空间站 (Mon Oct 25 09:42:57 2010, 美东)
You have nine balls, three of which are slightly heavier, and three of
which are slightly lighter than the normal three. All three balls in each
group have the same weight. All nine balls are identical otherwise. Your
mission is to determine the group of every ball using a pair of scales.
How many weighings are needed in order to ensure the accomplishment of
your mission?
Notes:
1. The difference of weight between the heavy and normal balls is not
necessarily equal to the difference of weight between the light and normal
balls.
2. The scales show only which side is heavier; it does not show the
difference of weight.
