数学GWD-2-13、23、30、32

lindaaniu · 发表于 2010-5-25 15:20:35

Q13:
An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?
(1)    The tens digit of n is a factor of the units digit of n.
(2)    The tens digit of n is 2.

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: A

Q23:
AMOUNT OF BACTERIA PRESENT
Time   Amount
1:00 P.M.   10.0 grams
4:00 P.M.   x grams
7:00 P.M.   14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A.   12.0
B.   12.1
C.   12.2
D.   12.3
E.   12.4
Answer: A

Q30:
                       E

      B      C

      A       D

In the figure, each side of square ABCD has length 1, the length of line segment CE is 1, and the length of line segment BE is equal to the length of line segment DE. What is the area of the triangular region BCE?

A.   1/3
B.   (?2)/4 (四分之根号二)
C.   1/2
D.   (?2)/2 （二分之根号二）
E.   3/4

answer：B
Q32:
What is the remainder when the two digit, positive integer x is divided by 3?
(1)    The sum of the digits of x is 5.
(2)    The remainder when x is divided by 9 is 5.

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: D

求解啊，我发现这种余数之类的代数问题做不来，有没有什么好方法？

msufcu · 发表于 2010-5-25 16:26:43

Q13
1）穷举 2开头不用说 3开头 33 36 39 44 48 55 66 77 88 99

msufcu · 发表于 2010-5-25 16:36:59

Q23
(x-10)/10=(14.4-x)/x

msufcu · 发表于 2010-5-25 16:43:37

Q32
1）举啊举啊举 14，41，23，32，50 除3全余2
2) 条件得x=9n+5 x/3余数2 （5/3）

msufcu · 发表于 2010-5-25 17:05:09

Q30 做出来c 坐等解答

lindaaniu · 发表于 2010-5-25 17:10:55

顶起来！第30道我也做出来是C。。。

lindaaniu · 发表于 2010-5-25 21:18:37

第三十题，自己给自己解，msufcu！！！！
不要把那个图看成立体的，这是一个平面，连接BD，延长EC与BD相交于一点，那么EC垂直BD，所以BCE的面积就等于1/2*1*（二分之根号二）

数学GWD-2-13、23、30、32

所属分类: GMAT考试

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