Re: [機統] 期望值相除
※ 引述《andysleep (Maydayisgod)》之銘言:
: X,Y互為獨立隨機變數
: E[X]/E[Y] = E[X/Y] 嗎?
: 要怎麼證明?
: 謝謝
隨便找個反例
X = 1 p=0.5 E[X] = 2
= 3 p=0.5
Y = 1 p=0.5 E[Y] = 2
= 3 p=0.5
X/Y = 1/3 p=0.25
= 1 p=0.5
= 3 p=0.25
E[X/Y] = 1/12 + 1/2 + 3/4 = 4/3 ≠ E[X]/E[Y] = 2/2 = 1
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