Re: [計量] pp1 DS 202
※ 引述《oranger (從新出發)》之銘言：
: 202.
: Each employee of Company Z is an employee of either Division X or Division Y,
: but not both. If each division has some part-time employees, is the ratio of
: the number of full-time employees to the number of part-time employees
: greater for Division X than for Company Z ?
: (1) The ratio of the number of full-time employees to the number of part-time
: employees is less for Division Y than for Company Z.
: (2) More than half of the full-time employees of Company Z are employees of
: Division X, and more than half of the part-time employees of Company Z are
: employees of Division Y.
: Ans: D
: 請大家幫忙了!! 謝謝~
引用PP解答的解法，但是也是不嚴謹的解法，看起來有點投機，希望有數學強者能分享
更嚴謹的思維。
題目問 f(x) + f(y) f(x)
______________ < ______ ?
p(x) + p(y) p(x)
條件1: f(y) f(z)
____ < ____
p(y) p(z) 把公司整體當成1 ，所以f(x)+f(y)=1， p(x)+p(y)=1
所以任意帶入數字檢查，ex: 0.8+0.2 0.8
_________ < _____
0.4+0.6 0.4
因為條件一的限制，所以 f(y)/p(y) 不能大於或等於 1 ，在滿足其條件下
代數字進去都會滿足 f(z)/p(z) < f(x)/p(x)
所以sufficient。
條件2: Division X 超過一半是full time ，Division Y超過一半是 part time
同理，帶入上述式子
ex: 0.6 0.4 0.6
________ + ___ < ____
0.4 0.6 0.4
所以sufficient
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◆ From: 61.229.185.109
※ 編輯: growthme 來自: 61.229.185.109 (09/05 01:50)
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09/08 23:30, , 1F
09/08 23:30, 1F
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