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当前版本由 349131oyxk 更新于2024-07-22 19:09:26 感谢由 349131oyxk 对此题目的解答所做出的贡献。
要验证命题III是否必然正确，我们可以首先确定由 (x, y, z, 5, 7) 构成的五个数的平均值为8。这意味着： [ \frac{x + y + z + 5 + 7}{5} = 8 ] [ x + y + z + 12 = 40 ] [ x + y + z = 28 ]
这表示 (x, y, z) 三个数的总和为28。
对于命题III：“五个数的极差（range）至少为2”：
我们知道最小的已知数是5，最大的已知数是7。如果 (x, y, z) 中所有的数都在5和7之间或等于5或7，那么极差仅为2（即 (7 - 5 = 2)）。但如果 (x, y, z) 中有任何一个数小于5或大于7，极差会增加。由于 (x, y, z) 之和为28，且平均值 ( \frac{28}{3} \approx 9.33)，至少有一个数大于7（以保持总和为28），所以极差至少为2。
综上，由于 (x, y, z) 的总和要求和它们相对于5和7的位置，我们可以推断极差至少为2，所以命题III是正确的。这里我们可以看出，至少有一个数字必须大于7，以保持总和为28，从而确保极差至少为2。
当前版本由 312686hchw 更新于2023-10-29 15:54:38 感谢由 312686hchw 对此题目的解答所做出的贡献。
range怎么可能是2？
当前版本由 谢谢谢汶君 更新于2018-05-10 10:52:26 感谢由 谢谢谢汶君 对此题目的解答所做出的贡献。
median=5 举例：3，4，5，7，21，错
II. 显然必须有个大于 9 的，正确
III. 值域≥2，正确
题目讨论
(如果对题目有任何的疑惑，欢迎在这里提出来，大家会帮你解答的哦~)
179600qn
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213983rdvm
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还有5和7啊，这样rang是5
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222458j
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可能因为用的是or吧，2 or more从逻辑上来看的话more肯定是成立的，那么2 or more整个就是成立的，不用管是2这个条件成不成立
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323927ed
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7呢
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好好学习336
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是的
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