[备考心经] 新G复习进行时7之数学面面观（CD制造）

这两天看了下OG上的数学部分，了解了下题型和考试内容，以下几点相当于是学习笔记。

一，题型OG上列出的有单选题、多选题和填空题，单选题跟之前的一样，包括关系比较题和直接选择结果的，多选题就是选择符合条件的多个答案。填空题，就是直接写出结果。填空题有个体验就是你要看清题目的要求，比如保留小数部分与否，保留几位等等，还有分数是写最简真分式，还是不用最简化等。

二，举几个自己认为比较有代表性的例子吧

1.One pen costs $0.25 and one marker costs $0.35. At those prices, what is the total
cost of 18 pens and 100 markers? $__________
本题计算简单，直接算出的结果可以是39.50，但你写39.5、39.500等等答案，都可以的，这就比我们的一些考试要好多了，不必要非要去注意保留几位小数的问题。

2.Rectangle R has length 30 and width 10, and square S has length 5. The
perimeter of S is what fraction of the perimeter of R ? _____/______
这个题，答案是1/4,你可以写任何与这个分数相等的其他结果。比如20/80，2/8等。

3.A merchant made a profit of $5 on the sale of a sweater that cost the
merchant $15. What is the profit expressed as a percent of the merchant’s
cost?
Give your answer to the nearest whole percent.___________%
这个题就明确的要求写出最接近的整数，所以结果就是33.

以上三题是关于填空的填法和审题的方面。

在接下来是击倒觉得还不太简单的题目。

1.Each employee of a certain company is in either Department X or Department Y, and there are more than twice as many employees in Department X as in Department Y. The average (arithmetic mean) salary is $25,000 for the employees in Department X and is $35,000 for the employees in Department Y. Wh ich of the following amounts could be the average salary for all of the employees in the company? Indicate all such amounts.

A $26,000
B $28,000
C $29,000
D $30,000
E $31,000
F $32,000
G $34,000

这道题印象中貌似是今年6G中出现过。这道题根据计算可以得到一个估计值，28,333dollars，但题目中有个关键词，more than ，这就是说，X的人是Y的人的两倍以上，也就表明平均工资比28,333会低些，答案就是AB了。如果做题的时候不注意的话，就很容易选错了。

2.A list of numbers has a mean of 8 and a standard deviation of 2.5. If x is a
number in the list that is 2 standard deviations above the mean, what is the
value of x ? x=__________

这道题读完不知道怎么算，看了答案才知道。求大侠讲解下这是怎么算的？

3.最后有点就是上次遇到了一个关于四分位点，中位点的题，感觉这种题就有点宽了，至少我感觉自己的高中和初中没学过，好像是大学的概率论与数理统计和随机过程的课里面学的，不去复习，就不知道怎么做了。

Eight hundred insects were weighed, and the resulting measurements, in milligrams, are summarized in the boxplot below.（OG P297第5题）

 (a) What are the range, the three quartiles, and the interquartile range of the
measurements?
(b) If the 80th percentile of the measurements is 130 milligrams, about how
many measurements are between 126 milligrams and 130 milligrams?

上面几题，以飨各位侠客，多多指教！时间问题，明天继续！