OG12-ds161 请牛牛们指教

sasha_wen

161. Beginning in January of last year, Carl made deposits of $120 into his account on the 15^th of each month for several consecutive months and then made withdrawals of $50from the account on the 15^th of no other transactions in the account on the 15^thof each of the remaining months of last year. There were no othertransactions in the account last year. If the closing balance of Carl’saccount for May last year was $2,600, what was the range of the monthlyclosing balance of Carl’s account last year?

1. Last year the closing balance of Carl’s account for April was less than $2,625.

2. Last year the closing balance of Carl’s account for June was less than $2,675.
答案 C

既不知道这题求什么，也看不懂OG的解释，请牛牛们指教，谢谢！

angel0428

这个range是指帐户中钱最多的时候-最少的时候得出的范围

sasha_wen

what was the range of the monthlyclosing balance of Carl’s account last year?这个是不是问去年每月银行账户结账范围？

tracyzhangcn

对对 同意5楼 偶错了

大荣

关键的是确认几月份开始取钱。大部分同意四楼的解法。但是从条件1推出的是May在存钱，而不是April。条件2推出的是6月份在取钱，而不是May。所以最大值在5月，1月和12月是可能的最小值，比较1月2600-500，12月2600-350，得出1月最小2100..

另外，这个题求range，应该最大值-最小值=500.不过DS题不用考虑算最终结果。

tracyzhangcn

April<2625; May=2600; June<2675

A) 对于april: 2600-120=2480满足<2625; 2600+50=2650不满足<2625; 所以证明april是在存；

B) 对于may: 2600+120=2720不满足<2675；2600-50=2550满足<2675；所以证明may是在取；

A)+B) 可知may之前在存，之后再取。 那么Jan: 2600-120*4=2120； Dec : 2600-50*7=2250;

那么range就可以求出来了:  2120-2600.

帮忙看看这么理解对么？

sasha_wen

大家帮帮忙，谢谢！

sasha_wen

ding

sasha_wen

顶