161. 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 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 account last year?
(1) Last year the 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
这题选c。看了og的解释，还是不明白，大侠们，能帮帮我吗？这题应该如何解决呢？谢谢作者: MAXworld 时间: 2010-6-2 17:24
首先题中说closing balance of May 是2600，closing balance of April 少于2625，那说明5月肯定是存钱了，因为如果是取钱，4月底少于2625，5月如果取乐50，那5月底的balance就少于2600了。同时，题中说六月底的balance少于2675,那说明六月肯定是取钱了，不然的话六月底的balance应该是2720（不符合题意）。所以综上所述c是对的。作者: MAXworld 时间: 2010-6-2 17:24
