GWD1-11

[邁向高等學府]

Mary persuaded n friends to donate $500 each to her election campaign, and then each of these n friends persuaded n more people to donate $500 each to Mary’s campaign. If no one donated more than once and if there were no other donations, what was the value of n?
(1) The first n people donated of the total amount donated.
(2) The total amount donated was $120,000.

答案爲D
麻煩解釋…感激不盡

[Pufa]

屋，又讓我看了好久...
你題目貼錯了，第一個選項裡面少了1/16，下次要注意一下阿 ~


mary說服n個人各捐500給他，這n個人又各自說服n個人捐500。

500n+(500)(n^2)=總金額

(1) 500n=(1/16){500n+500n^2} n=16
(2) 500n+(500)(n^2)=120000 n=15

[邁向高等學府]

不好意思，造成困擾，從檔案轉貼時好像會漏字，一時未查

[Pufa]

呵呵
我第一選項的答案算錯了，
n=15/16才對，
這麼醜的答案不曉得有沒有錯。

[Behemoth]

http://www.formosamba.com/phpBB3/viewtopic.php?t=2840

發問前請先參考置頂連結總整理~

另外,pufa該打屁股喔,都老人了還不查查有沒有連結先呀~~~

[Pufa]