以下是引用xinxuan_zhu在2006-12-3 15:51:00的发言：求助tt-5-7,9,28,30,37，多谢了！！
MATHE 5
Q37:
Of the families in City X in 1994, 40 percent owned a personal computer. The number of families in City X owning a computer in 1998 was 30 percent greater than it was in 1994, and the total number of families in City X was 4 percent greater in 1998 than it was in 1994. What percent of the families in City X owned a personal computer in 1998?
A. 50%
B. 52%
C. 56%
D. 70%
E. 74%
Answer: A
过程：设９４年的电脑数和家庭数为x,y,则９４年的时候x/y=０．４，到９８年根据题目意思就是求1.3x/1.04y*100%=50%
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Q30:
Joanna bought only $0.15 stamps and $0.29 stamps. How many $0.15 stamps did she buy?
(1) She bought $4.40 worth of stamps.
(2) She bought an equal number of $0.15 stamps and $0.29 stamps.
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
分别假设两种邮票的数目为x,y
由(1),0.15x+0.29y=4.40 不要小看这个二元一次方程,实际上因为x,y只能取整数,楼主只要把整数验算带进去就好;
由(2),因为x=y,但是并没有给出买了多少钱等相关信息,所以不能推出结论
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Q28:
Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day. If r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper B, which of the following expresses r in terms of p?
A. 100p / (125 – p)
B. 150p / (250 – p)
C. 300p / (375 – p)
D. 400p / (500 – p)
E. 500p / (625 – p)
Answer: 上面有gg已经说了
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Q9:
In the xy-plane, the point (-2, -3) is the center of a circle. The point (-2, 1) lies inside the circle and the point (4, -3) lies outside the circle. If the radius r of the circle is an integer, then r =
A. 6
B. 5
C. 4
D. 3
E. 2
Answer: B
因为(-2,1)在圆内,则它与点之间的距离必定是小与r的，距离为4,而(4,-3)与圆心的距离是6.
因为r为5(题目说了r is an integer)
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Q7:
What is the value of │x + 7│?
(1) │x + 3│= 14
(2) (x + 2)2 = 169
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. C, 由(1), x的可能取值为11或者-17,带入原式发现有两个解;
由(2),x的取值可以是-15或者11,带入也是有两个解,而1,2同用的话则x为11很容易算出答案的..
C, 由(1), x的可能取值为11或者-17,带入原式发现有两个解;
由(2),x的取值可以是-15或者11,带入也是有两个解,而1,2同用的话则x为11很容易算出答案的..
C, 由(1), x的可能取值为11或者-17,带入原式发现有两个解;
由(2),x的取值可以是-15或者11,带入也是有两个解,而1,2同用的话则x为11很容易算出答案的..
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发表于 2006-12-3 15:51:00
楼主
