OG数学题求解

imddung

OG13 5.5第218题求翻译和中文解答~

List T consists of 30 positive decimals, none of which is an integer, and the sum of the 30 decimals is S.The estimated sum of 30 decimals,E, is defined as follows. Each decimal in T whose tenths digit is even is rounded up to the nearest integer, and each decimals in T whose tenth digit is odd is rounded down to the nearest integer; E is the sum of the resulting integers. If 1/3 of the decimals in T have a tenth digit that is even, which of the following is a possible value of E-S?
I. -16
II.6
III.10

啊~~两天了都木有人回帖，是因为真的太难了么？
那先求题目翻译好了~~求大牛

imddung

列表T包含30 个正小数,其中没有一个是整数,30个小数的总和是S。30小数的estimated sum,E,是定义如下。T中的每一个十位数是偶数的数is rounded up to the nearest integer,T中的每一个十位数是奇数的数is rounded down to the nearest integer;E是这两个数的总和。如果T中1/3的小数的十位数字是偶数,甚至,那么E-S可能值是？

以上是我自己翻译了一下，主要不理解的地方：
1、estimated sum（估计总和？神马意思？前面不是说了30个的和是S么？）自己解答：相当于是另外定义了一个数，不矛盾
2、is rounded up to the nearest integer、is rounded down to the nearest integer是神马意思？

howie0420

啊 仔细看了下解释看懂啦 这道题不是很难 就是取极端例子 加上做很多假设 最后算出一个区间 再选答案~~
主要还是英文的问题

krusher

1 估计值
2 四射五入的意思

krusher

仔细读了遍题，rounded up ,rounded down 是取整的意思， 十分位偶数就向上取整，奇数向下取整