幾個新PP裡的問題請教大家!!

[stwang]

1)Each employee on a certain task force is either a manager or a director. What percent of the employees on the task force are directors?
(1)The average salary of the managers on the task force is $5000 less than the average salary of all employees on the task force.
(2)The average salary of the directors on the task force is $15000 greater than the average salary of all employees on the task force.

答案給(C)

2)The rate of a certain chemical reaction is directly proporational to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?
(A) 100% decrease
(B) 50% decrease
(C) 40% decrease
(D) 40% increase
(E) 50% increase

答案給(D)

3)A certain library assesses fines for overdue books as follows, on the first day that a book is overdue, the total fine is $0.10. For each additional day that the book is overdue, the total fine is either increased by $0.3 or doubled, whichever results in the lesser amount. What is the total fine for a book on the fourth day it is overdue?
(A) 0.6
(B) 0.7
(C) 0.8
(D) 0.9
(E) 1.0

答案給(B)
我想請問紅色部分是什麼意思勒?

以上問題請各位大大解答喔

[scujean]

3)A certain library assesses fines for overdue books as follows, the total fine is either increased by $0.3 or doubled, whichever results in the lesser amount. What is the total fine for a book on the fourth day it is overdue?
(A) 0.6
(B) 0.7
(C) 0.8
(D) 0.9
(E) 1.0

答案給(B)
我想請問紅色部分是什麼意思勒?

以上問題請各位大大解答喔

這題好像少打題目..我也想知道做法..

[stwang]

3)A certain library assesses fines for overdue books as follows, the total fine is either increased by $0.3 or doubled, whichever results in the lesser amount. What is the total fine for a book on the fourth day it is overdue?
(A) 0.6
(B) 0.7
(C) 0.8
(D) 0.9
(E) 1.0

答案給(B)
我想請問紅色部分是什麼意思勒?

以上問題請各位大大解答喔

這題好像少打題目..我也想知道做法..

我已經修改過囉...
請指教...

[micki]

置頂不是有規定一篇一題?

[scujean]

3)A certain library assesses fines for overdue books as follows, on the first day that a book is overdue, the total fine is $0.10. For each additional day that the book is overdue, the total fine is either increased by $0.3 or doubled, whichever results in the lesser amount. What is the total fine for a book on the fourth day it is overdue?

whichever results in the lesser amount.→這兩種方法，哪一種會導致較少的罰金時，就取那一種方法算出的結果。

[Cd上的做法]
那么第一天是0.1，第二、第三天显然是double比较合算，到第四天是+$0.3合算，也就是这样的一个罚款变化，0.1->0.2->0.4->0.7

1)Each employee on a certain task force is either a manager or a director. What percent of the employees on the task force are directors?
(1)The average salary of the managers on the task force is $5000 less than the average salary of all employees on the task force.
(2)The average salary of the directors on the task force is $15000 greater than the average salary of all employees on the task force.

[CD上的做法]
假设有100个员工，director有d个，manager有100－d个
t平均数，利用总的薪水相等列式子

t*100=(t-5000)(100-d)+(t+15000)d

2)The rate of a certain chemical reaction is directly proporational to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?
(A) 100% decrease
(B) 50% decrease
(C) 40% decrease
(D) 40% increase
(E) 50% increase

某rate和A^2成正比，和B成反比，可以表示成R*B/A^2=k， k,R是常數。B變成2倍的話，要保持R不變，A^2也要變2倍，所以A只要根號2倍，根號2，接近40%

對了，你要把題目分成3題來問才符合版規...不然這篇之後會被砍掉

[stwang]

謝謝scujean的解答唷....

關於一篇只能貼一個題目 不好意思 我沒有注意到
下次改進唷