PP PS 1 Q 71

[nemolee]

71. 8312-!-item-!-187;#058&005967
71. On July 1 of last year, the total number of employees at Company E was decreased by 10 percent. Without any change in the salaries of the remaining employees, the average (arithmetic mean) employee salary was 10 percent more after the decrease in number of employees than before the decrease. The total of the combined salaries of all of the employees at Company E after July 1 last year was what percent of that before July 1 last year?

(A) 90%
(B) 99%
(C) 100%
(D) 101%
(E) 110%

ANS: B

不知對題目的理解有沒有錯　＝＝＞　題目問：在7/1號之後，E公司所有員工的薪支總合是 7/1號之前的多少百分比?

設原來總人數有X人， X- 10% = 90%X（公司剩下不走的人)
題目又說減少之10%員工的薪水mean 比 7/1之前的 mean 多了 10%

完蛋了~ 就這樣一直算了好幾次，算不到 99%, 怎麼算都是 90%...

拜請高人.. 指點，謝謝。

[Huang Hsin-Yi]

71. 8312-!-item-!-187;#058&005967
71. On July 1 of last year, the total number of employees at Company E was decreased by 10 percent. Without any change in the salaries of the remaining employees, the average (arithmetic mean) employee salary was 10 percent more after the decrease in number of employees than before the decrease. The total of the combined salaries of all of the employees at Company E after July 1 last year was what percent of that before July 1 last year?

(A) 90%
(B) 99%
(C) 100%
(D) 101%
(E) 110%

ANS: B

不知對題目的理解有沒有錯　＝＝＞　題目問：在7/1號之後，E公司所有員工的薪支總合是 7/1號之前的多少百分比?

設原來總人數有X人， X- 10% = 90%X（公司剩下不走的人)
題目又說減少之10%員工的薪水mean 比 7/1之前的 mean 多了 10%

完蛋了~ 就這樣一直算了好幾次，算不到 99%, 怎麼算都是 90%...

拜請高人.. 指點，謝謝。

關鍵在紅色那句話是陷阱
改變後每人薪水是不一樣滴,是根據它說平均不同
因此 Salary要有 S(after) 和 S(before)兩個代數去設聯立
就可求出99%

這種題目還真恐怖勒

[luachen]

設原本人數X，平均薪資Y=>總薪資為XY
之後人數變為0.9X，平均薪資變成1.1Y=>總薪資變成0.99XY

故為99%

答案(B)

[nemolee]

簡潔有力，感謝