og11 DS的141题

pourquoiwhy

 11版og第141题的题目是什么意思啊····脑子晕晕的看不明白了···

wensky

建议把题目贴出来，这样好讨论

pourquoiwhy

141.On Jane's credit card account, the average daily balance for a 30-day billing cycle is the average (arithmetic mean)of the daily balances at the end of each of the 30days.At the beginning of a certain 30-day billing cycle,Jane's credit card account had a balance of $600.Jane made a payment of $300 on the account during the billing cycle.If no other amounts were added to or subtracted from the account during the billing cycle, what was the average daily balance on Jane's account for the billing cycle?

(1)Jane's payment was credited on the 21st day of the billing cycle.

(2)The average daily balance through the 25th day of the billing cycle was $540

谢谢各位啦·

lunar870510

这题选什么？

zjpopo

我第一次看到这题也晕了。还是阅读问题。应该选Ｄ是吧？
(1)Jane's payment was credited on the 21st day of the billing cycle　　　(600*20+300*10)/30

(2)The average daily balance through the 25th day of the billing cycle was $540    (540*25+30*5)/30

[此贴子已经被作者于2009-1-18 16:36:25编辑过]

pourquoiwhy

是选D没错，解释我能看懂·就是这个题目本身··阅读问题·

jamily_2008

再问,还是没有读懂...请大牛们帮忙翻译一下题目把~~

在(1)中为什么是<x*600+(30-x)*300>/30呢？是账户里的600元钱到第21天时变为300了的意思吗？

jikuren

141.On Jane's credit card account, the average daily balance for a
30-day billing cycle is the average (arithmetic mean)of the daily
balances at the end of each of the 30days.At the beginning of a certain
30-day billing cycle,Jane's credit card account had a balance of
$600.Jane made a payment of $300 on the account during the billing
cycle.If no other amounts were added to or subtracted from the account
during the billing cycle, what was the average daily balance on
Jane's account for the billing cycle?

信用卡的平均每日余额就是每日余额的平均值。如果第一天的余额是600，当月只发生了一笔还款300，除此外没有其他交易。问这个月的平均每日余额是多少？

(1)Jane's payment was credited on the 21st day of the billing cycle.

还款发生在第21天；（20*600+10*300）/30

(2)The average daily balance through the 25th day of the billing cycle was $540

前25天平均余额540。（540*25+300*5）/30

[此贴子已经被作者于2009-3-8 21:46:07编辑过]

jamily_2008

明白啦~~谢谢啊!

RTP

（540*25+300*5）/30 这个式子对吗？

这样算出来的结果跟OG解释的结果不同啊

OG：[x(600)+(25-x)(300)]/25，得出x=20，

再用[x(600)+(30-x)(300)]/30得出