GWD31-3 三道数学！求助~~~~~~

dolorez

Q10:  第二个为什么可以呢？
If $1,000 will be deposited in a bank account and I is the dollar amount of interest earned from the original deposit, represented as I = 1000 {(1 + r/100)n – 1}, and the annual interest rate is r percent, is r > 8 percent?
(1)    The deposit earns a total of $210 in interest in the first 2 years.
(2)    (1 + r/100)2 > 1.15

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Q29:（2）中是什么意思呢？？
Is the integer n odd?    
(1)      n is divisible by 3.
(2)      2n is divisible by twice as many positive integers as n.
    
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Q32:   为什么答案是D呢？？（2）中one  of numbers又不一定是中位数啊
A certain list consists of 3 different numbers.  Does the median of the 3 numbers equal the average (arithmetic mean) of the 3 numbers?
(1)    The range of the 3 numbers is equal to twice the difference between the greatest number and the median.
(2)      The sum of the 3 numbers is equal to 3 times one of the numbers.
    
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

bqu002

是啦，factor的确是因数，但是这题的意思是能被2n整除的正整数的个数是能被n整除的2倍，我就用因数概括省事了。

dolorez

噢。。。原来是这样的。。。多谢！！！

flyzoe小猪

三个是不是min的就是中位数，要么是max，你应该明白...

那么三个数的和不可能是max的三倍，对吧，那就是中位数或者min的三倍，对吧

如果是min的三倍，就是我刚刚列的式子S=3A，如果是中位数的三倍，你应该明白了吧～

flyzoe小猪

不对吧，那样的应该加上factor吧...

dolorez

不理解呢，，，，题目说了三个数不等阿，所以（2）中的那个数万一不是中位数不就不能成立麽？？

bqu002

不好意思，看晕了，你Q10的（2）貌似有点问题，r求出来是大于一个负数，所以貌似应该不可以

bqu002

29的（2）意思就是2n的正整数因数的数量是n的2倍

bqu002

Q10,第二个可以解出来R的值啊，所以就可以知道是不是大于8%了

flyzoe小猪

33题的(2),假使他不是中位数，是最小的，那么和S=3A（A为最小的），可推出，三个数相等，平均数还是等于中位数的...我说的你能明白吗？