发布时间 : 星期六 文章PP-DS1-2更新完毕开始阅读
(2) 藍球：紅球 = 3 : 1
(1)+(2) 可知 綠球：紅球 = (1/2) : (1/3)
--------------------------------------------------------------------------------------------------------------------------------------------------------
104. 9643-!-item-!-187;#058&006681 What is the value of x ?
(1) y - x = y - 6
(2) x + 2y = 10
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】A
【思路】又是個典型低分區考題。
(1) 同減y，解得 x = 6
(2) 顯然不充分，因為不知y值。
--------------------------------------------------------------------------------------------------------------------------------------------------------
105. 9789-!-item-!-187;#058&006817
What is the number of members of Club X who are at least 35 years of age?
(1) Exactly
(2) The 64 women in Club X constitute 40 percent of the club’s membership.
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】C
【思路】這種題目不必細看，凡是題目求數字條件卻只給比例的，都錯。
(1) 只能判斷出35歲以上的成員佔了1。 4(2) 只能判斷出總人數 = 64/0.4 = 160。 (1)+(2) 可知35歲以下人數 = 160 x
1434 of the members of Club X are under 35 years of age.
= 40。
--------------------------------------------------------------------------------------------------------------------------------------------------------
106. 9843-!-item-!-187;#058&006850 What was Jean's insurance premium in 1995 ?
(1) The ratio of Jean’s insurance premium in 1995 to her insurance premium in 1994 was
(2) Jean’s insurance premium in 1995 was 20 percent more than her insurance premium in 1994. -------------------------------------------------------------------------------------------------------------------------------65.
------------------------- 【答案】E
【思路】同上題，凡是題目求數字條件只給比例的，都錯。
(1) 只給比例推不出金額。 (2) 只給比例推不出金額。
(1)+(2) 兩個比例還是推不出金額。
--------------------------------------------------------------------------------------------------------------------------------------------------------
107. 9897-!-item-!-187;#058&006904
A combined total of 55 lightbulbs are stored in two boxes; of these, a total of 7 are broken. If there are exactly 2 broken bulbs in the first box, what is the number of bulbs in the second box that are not broken?
(1) In the first box, the number of bulbs that are not broken is 15 times the number of broken bulbs.
(2) The total number of bulbs in the first box is 9 more than the total number of bulbs in the second box. -------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】D
【思路】先列表記下已知條件以助判斷，只要x能算出唯一解，條件就充分：
箱子一 箱子二
(1) 48 – x = (15)(2)，條件充分。
(2) [2 + (48 - x)] = (5 + x) + 9，條件充分。
--------------------------------------------------------------------------------------------------------------------------------------------------------
108. 10385-!-item-!-187;#058&007204
Three friends rented a car for a week and divided the cost equally. What was the total cost of renting the car?
(1) If the three friends had kept the car for a second week, they could have obtained the two-week rate, which was 1.5 times the cost of a one-week rental.
(2) If a fourth friend had joined the three friends and the cost had been divided equally among the four friends, the cost to each of the original three would have been reduced by $15.
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】B
【思路】凡是題目求數字條件只給比例的，都錯。
(1) 只給比例推不出金額。
(2) 假設3個人時每個人要負擔x元，可知 4(x - 15) = 3x，條件充分。
破 2 5
沒破 48-x x
--------------------------------------------------------------------------------------------------------------------------------------------------------
109. 10439-!-item-!-187;#058&007237 If R = 1 + 2xy + x2y2, what is the value of xy ?
(1) R = 0
(2) x > 0
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】A
222【思路】(a?b)?a?2ab?b
2(1) 可知 (xy?1)?0? xy = -1
(2) 顯然不充分，不知y值。
--------------------------------------------------------------------------------------------------------------------------------------------------------
110. 10493-!-item-!-187;#058&007240 If zn = 1, what is the value of z ?
(1) n is a nonzero integer. (2) z > 0
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】C
【思路】第一，在AT數學中，所有的未知數都是實數；大家忘了棣美弗定理這檔事吧。 第二，在AT中所有的未知數都必須是唯一解。 在實數的前提下，答案只剩三種可能：
(A) n=0而z是任意數 (B) n是≠0的任意數而z＝1 (C) n是≠0的偶數而z＝-1
(1) 只排除了可能性(A) (2) 只排除了可能性(C)
(1)+(2) 保證了z=1是唯一解，條件充分。
--------------------------------------------------------------------------------------------------------------------------------------------------------
111. 10884-!-item-!-187;#058&007442
If x, y, and z are positive integers, what is the remainder when 100x + 10y + z is divided by 7 ?
(1) y = 6 (2) z = 3
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】E
【思路】x, y, z 其實就是百位、十位與個位數。7並沒有只看部分位數就能判斷倍數的法則。
(1) 只知道十位數。 (2) 只知道個位數。
(1)+(2) 只知道個個位數與十位數。
--------------------------------------------------------------------------------------------------------------------------------------------------------
112. 11176-!-item-!-187;#058&007606
Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?
(1) If the admission fee had been $0.75 less and 100 more people had attended, the club would have received the same amount in admission fees.
(2) If the admission fee had been $1.50 more and 100 fewer people had attended, the club would have received the same amount in admission fees.
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】C
【思路】總入場費 = (入場費) x (進場人數)。 設入場費為$x，進場人數為n。
(1) 只能推出 (x - 0.75)(n + 100) = xn (2) 只能推出 (x + 1.5)(n -100) = xn (1)+(2) 兩條件式解兩未知數，條件充分。
--------------------------------------------------------------------------------------------------------------------------------------------------------
113. 11760-!-item-!-187;#058&007855
For a certain set of n numbers, where n > 1, is the average (arithmetic mean) equal to the median?
(1) If the n numbers in the set are listed in increasing order, then the difference between any pair of successive numbers in the set is 2.
(2) The range of the n numbers in the set is 2(n - 1).
-------------------------------------------------------------------------------------------------------------------------------------------------------- 【答案】A
【思路】求平均數須知道每個數字的大小；求中位數則須知道數字間的相對大小。
(1) 這n個數字是一個公差為2的等差數列，可知平均數與中位數相同，即 (首項+末項) / 2。 (2) 只知道全距，條件明顯不充分。
-------------------------------------------------------------------------------------------------------------------------------