GWD-25中数学题请教。谢谢NN们

Q10

     The sides of a square region, measured to the

         nearest centimeter, are 6 centimeters long. The

         least possible value of the actual area of the

         square region is

A.36.00 sq cm

B.35.00 sq cm

C.33.75 sq cm

D.30.25 sq cm

E.25.00 sq cm

为什么选择C而不是D.nearest centimeter 之后least possible我认为是5.5^2

Q13

If the average (arithmetic mean) of the assessed values

of x houses is $212,000 and the average of the assessed

values of y other houses is $194,000, what is the average

of the assessed values of the x+y houses?

(1)    x+y=36

(2)    x=2y

     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.

Answer:

答案是C。为什么不是B

Average=（212，000x+194000y）/(x+y).如果x=2y，那么可以将x全部用y表示，不是就可以算出average的值么。答案给的是C。但是我认为B没有错。

If M is a positive integer, then M^3 has how many digits?

(1) M has 3 digits.

(2) M^2 has 5 digits

这题的答案是E。可否请NN们帮忙解答一下。谢谢。

Q32.

Last year in a group of 30 businesses, 21 reported a net profit and

15 had investments in foreign markets. How many of the businesses

did not report a net profit nor invest in foreign markets last year?

(1) last year 12 of the 30 businesses

   reported a net profit and had invest-

   ments in foreign markets.

(2) last year 24 of the 30 businesses

   reported a net profit or invested in

这题我的答案是D。可是答案给的B。希望大家帮忙解答一下。

谢谢大家啦。

If M is a positive integer, then M^3 has how many digits?

(1) M has 3 digits.

(2) M^2 has 5 digits

举个例子，M=100和M=300，同时满足两个条件，但是m^3分别是7位数和8位数，因此不能确定～

恩。谢谢啦。

个人认为剩下的三道题你的答案都是正确的，至少我的答案跟你一样。

gwd的大案都只是参考答案，不是标准答案。