Og11-Diagnostic-Q31

[Huang Hsin-Yi]

Is the standard deviation of the set of measureents X1,X2,X3,X4,........X20 less than 3

(1) The variance for the set of measurements is 4
(2) For each measurement, the difference between the mean and the measurement is 2

請問那位數學高手 指教這題牽涉那些觀念去解題
實在看的霧颯颯

[Huang Hsin-Yi]

是不是我問的問題太簡單

[小花]

感謝問這一題
讓我有機會在翻閱塵封已久的OG11

這題烤標準差與變異數
觀念在OG11 P115頁

Is the standard deviation of the set of measureents X1,X2,X3,X4,........X20 less than 3

(1) The variance for the set of measurements is 4
(2) For each measurement, the difference between the mean and the measurement is 2

首先需了解標準差(S)的定義
Variance(變異數)=(Xn-Xmean)^2
也就是數列上各個數與平均數的差再平方
Standard deviation=(各個數的變異數相加/n )然後開根號

(1)每個數的變異數是4
題目給有20個數 n=20
4*20=80
S=(80/20)開根號=2
小於3 符合
(2)the difference between the mean and the measurement is 2
然後去看變異數的定義Variance(變異數)=(Xn-Xmean)^2
題目給的條件就是括弧裡給的東東
V=2^2=4
V=4 S 應該可以知道了巴
算法和(1)一樣
S=2 符合 故D

寫的這麼囉唆 不知道看的懂嗎
有問題歡迎再發問
建議看一下OG11 P115頁
會比較清楚

變異數是滿重要的觀念了解各個數分散的程度
MBA 相信應該會遇到 統計和財務都需用到這觀念

[Huang Hsin-Yi]

非常謝謝小花大大
我終於弄懂了