Prep-DS-202

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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.

答案：D。求解题思路。

imjar

分享个牛人的答案

以下是eced大大的有算式驗證法: (推薦)
F(x)/P(x) > F(z)/P(z) ? F(z)=F(x)+F(y) ; P(z)=P(x)+P(y)
(1) F(y)/P(y) < F(z)/P(z)
=>[ F(z)-F(x)] / [ P(z)-P(x)] < F(z)/P(z)
=> P(z)F(z)-P(z)F(x) < F(z)P(z)-F(z)P(x)
=>F(x)/P(x) > F(z)/P(z)
sufficient

(2) F(x) > F(y); P(y) > P(x)
F(x)/P(x) > F(y)/P(y)=[F(z)-F(x)]/[P(z)-P(x)]
F(x)P(z)-F(x)P(x) > P(x)F(z)-P(x)F(x)
F(x)/P(x) > F(z)/P(z)
sufficient

以下是我的 two cents:
(1) X部門和Y部門相加之後的full-time/part-time比是公司整體的full-time/part-time比例.
    把公司整體的full-time/part-time比看作是1的話,不難看出以下的關悉
(2) 這句話就是說X部門有高於公司整體的full-time/part-time比例. 由(1)的公式,把公司整體的full-time/part-time比例看作1,再代入假設的數字驗算一下. ex, 1/1<0.6/0.4.