上一片，平均数用“移多补少”给出了“一般水平”。可要是队伍里混进一个特别大的值，平均数会被拽着跑。有没有一个更稳的数字，只说“中间”在哪？Last leaf, the mean described the “typical level” by pouring from the full into the empty. But when one huge value shows up, the mean gets dragged along. Is there a steadier number that simply marks where the middle is?
第 1 步：先排队，再找中间Step 1: Line up first, then find the middle
五个孩子头顶各有一个数，谁才是这排数的“中间水平”？Five kids, one number each. Which one is the “middle level” of the row?
机器人让大家从小到大排好队：3、5、7、9、11。正中间站着的 7，比两个大、比两个小，它就是中位数（median）。找中位数第一步永远是排序——队伍没排好，中间那个座位谁也不敢坐。The robot lines them up from smallest to largest: 3, 5, 7, 9, 11. The one exactly in the middle, 7, has two numbers on each side. That is the median. Step one is always sorting — without a proper line-up, nobody can claim the middle seat.
五个数正好有一个人站中间。要是六个数呢？Five numbers leave exactly one in the middle. What about six?
第 2 步：偶数个，取中间两个的平均Step 2: An even count — average the middle two
中位数只认“位置”，不看数值大小。偶数个数排好队后，中间会空出两个位置。比如 6、8、11、14、16、19，中间是 11 和 14，把它们平均一下：(11 + 14) ÷ 2 = 12.5，12.5 就是中位数。平均数要摊全部数，中位数只在“正中间”落点。The median only cares about position, never size. With an even count, two seats fall in the middle. In 6, 8, 11, 14, 16, 19 the middle pair is 11 and 14 — average them: (11 + 14) ÷ 2 = 12.5, and that is the median. The mean shares out every value; the median just marks the very centre.
两个数都能说“一般水平”，真遇上怪数据，谁更稳？Both can describe “typical” — but when odd data shows up, which one holds steadier?
第 3 步：它不怕极端值Step 3: It shrugs off extreme values
5 位员工月薪 3000～7000，平均和中位数都是 5000。老板带着 20000 的月薪加入后：平均数被拉到 7500，一下涨了 50%；中位数只从 5000 挪到 5500，几乎不动。聊工资、房价这种“个别值特别大”的数据，中位数往往更贴近大多数人的真实水平。Five employees earn 3000–7000 a month; the mean and the median are both 5000. When the boss joins at 20000, the mean shoots up to 7500 — a 50% jump — while the median only inches from 5000 to 5500. For salaries, house prices and other data with one huge outlier, the median gets closer to most people’s reality.
🎮 排队找中间：4 轮挑战🎮 Find the middle: 4 rounds
前两轮练排队找中位数（第 2 轮是偶数个，要动笔算一下）；后两轮猜一猜：极端值来了，平均数和中位数谁更稳？The first two rounds drill the line-up (round 2 has an even count — you’ll do a quick calculation). The last two ask: when an extreme value arrives, which holds steadier, the mean or the median?
一句话记住它：中位数 = 排好队后站在正中间的那个数；它认位置、不认大小，所以不怕极端值。Remember it in one line: the median is the value in the exact middle once everything is lined up. It counts position, not size — so extreme values don’t scare it.
第一步永远是从小到大排序Step one is always sorting from smallest to largest奇数个取中间一个；偶数个取中间两个的平均Odd count: take the middle value; even count: average the middle two有个别特别大的值时，它比平均数更能代表大多数With a huge outlier around, it represents most people better than the mean
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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