题没读明白~~~求牛牛

zscsl

DS：
Beginning in January of last year, Carl made deposits of $120 into his account on the 15th of each month for several consecutive months and then made withdrawals of $50 from the account on the 15th of each of the remaining months of last year. There were no other transactions in the account last year.If  the closing balance of Carl's account for May of last year was $2600, what was the range of the monthly closing balances of Carl's acount last year?
(1)Last year th closing balance of Carl's account for April was less than $2625

(2)Last year the closing balance of Carl"s account for June was less than $2675

O(∩_∩)O谢谢~~~~

poorxiaodai

C 吧？
（1） --->5月是+120，
(2) ---->6月是-70.。。。。。

zscsl

C 吧？
（1） --->5月是+120，
(2) ---->6月是-70.。。。。。

-- by 会员 poorxiaodai (2009/12/21 11:18:04)

题目什么意思哟。。没读明白~~~谢谢你哈。。帮我解释一下。。。

poorxiaodai

应该是说前面几个月每个月村120，后面每个月取50. 看条件能不能确定转折点在几月。

zscsl

应该是说前面几个月每个月村120，后面每个月取50. 看条件能不能确定转折点在几月。

-- by 会员 poorxiaodai (2009/12/21 11:38:21)

哪怎么确定哟。。。我数学太不好了。。(*^__^*) 嘻嘻……

charch

5月底2600，6月底<2675，说明6月是取钱的
如果5月也是取钱的话，4月底就是2650。现在给出条件4月底<2625，可推出5月是存钱的