求助OG12里的数学题

欧洋彤 · 发表于 2010-3-28 22:23:11

DS: Is the standard deviation of the set of measurements X1,X2,X3,X4...,X20 less than 3?
(1)The variance for the set of measurements is 4
(2)For each measurement, the difference between the mean and that measurement is 2
这道题是什么意思？还有关于标准差和方差的东西需要掌握到什么程度？
DS:In the XY-plane,if line K has negative slope and passes through the point (-5,r),is the X-intercept of line K positive?
(!)The slope of line is -5
(2)r>0
答案选E，我选A , 其实也没明白这题在说什么。
DS:Of the 66 people in a certain auditorium, at most 6 people have their birthdays in any given month, Does at least one person in the auditorium have a birthday in January?
(1)More of the people in the auditorium have their birthday in Februry than in March.
(2)Five of the people in the auditorium have their birthday in March.
这道题说的是什么意思啊？完全不理解。。。
PS：The average (arthmetic mean) of the integers from 200 to 400, inclusive, is much greater than the average of the integers from 50 to 100, inclusive?
A.150 B 175 C200 D 225 E 300
这道题有什么简单的方法么？
ps: John deposited $10000 to open a new savings account that earned 4 percent annual interest, compounded quarterly. If there were no other transactions in the account, what was the amount of money in John's account 6 months after the account was opened?
A$10100 B $10101 C $10200 D $10201 E $10400
答案选D 我选C 为什么？

O(∩_∩)O哈哈~，题有点多，大家帮帮忙吧

求助OG12里的数学题

所属分类: GMAT考试

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