GWD 3 Math

rachel_zhang

有两道题想跟大家问问。

Q17:

The number of defects in the first five cars to come through a new production line are 9, 7, 10, 4, and 6, respectively.  If the sixth car through the production line has either 3, 7, or 12 defects, for which of theses values does the mean number of defects per car for the first six cars equal the median?

 

 

I.                    3

II.                 7

III.               12

 

 

A.         I only

B.          II only

C.         III only

D.         I and III only

E.          I, II, and III

我选择B，但答案是D。为什么？没有想通

Q24:

At a certain company, each employee has a salary grade s that is at least 1 and at most 5.  Each employee receives an hourly wage p, in dollars, determined by the formula p = 9.50 + 0.25(s – 1).  An employee with a salary grade of 5 receives how many more dollars per hour than an employee with a salary grade of 1?

 

A.     $0.50

B.     $1.00

C.     $1.25

D.     $1.50

E.      $1.75

我选择B。P5-P1=0.25(5-1)-0.25(1-1)=1.00 为什么答案是C？

还有

Q29:

The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998.  Was the annual rent collected by the corporation from the building more in 1999 than in 1997?

(1)
                      x > y

(2)   xy/100< x – y

                  

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.

 

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 这道题目没有看明白，因为根据提干，不给任何调节都可以判断1999比1997多了啊。太愚钝了，望高人指教。

 

 

graysytl

第一题，要求中数（median）和平均数相等(mean).

把原来5个数排列一下，4，6，7，9，10；

如果第6个数是3，那么mean是6.5 median是6.5； 符合要求

如果第6个数是7，那么mean是 43/3， median是7；不符合

如果第6个数是12，那么mean是8，median是8；符合。

如果还是不明白，请复习mean和median的概念。

第二题 我认为你做对了

第三题题目意思是这样的x percent more in 1998 than in 1997 说明 98〉87

 y percent less in 1999 than in 1998. 说明 98〉99，

所以让你比较 97和99。

根据条件可得， 以a,b,c 代表97，98，99，则 b=a(1+x/100), c=b(1-y/100)

所以你要比较的是 1/(1+x/100) 和 1-y/100

答案是b

kenlin4590

同意上面說的

rachel_zhang

非常感谢