考试吧整理：GMAT考试真题及解析

Data Sufficiency


　　What is the average (arithmetic mean) of a, b, and c ?


　　(1)a + 2b + 3c=10


　　(2)3a + 2b + c=14


　　Answer Choices


　　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:


　　C


　　Explanation:


　　The average of a, b, and c is a+b+c/3. Statement (1) says that a+2b+3c=10, but there is not enough information to determine the value of a+b+c. Thus, statement (1) alone is not sufficient. Similarly, the equation statement (2) also fails to give enough information, so statement (2) alone is not sufficient. If the equations in statements (1) and (2) are added together, term by term, the result is 4a+4b+4c=24, which means that a+b+c=6. The average is therefore 6/3=2. Thus, BOTH statements TOGETHER are sufficient to answer the question. The best answer is C.




　　GMATIR真题：密码排列


　　有个人忘了自己的两个4位数的密码，第一个密码只知道第一个数字是5，其他数字都比5大且都distinct，第二个密码4个数加起来是6，问两个密码各有几种排列，我选的是都是24。by 天天年年1995


　　【补充】原寂静的第11题


　　第一种描述是对的，答案24没问题


　　第二种它加起来是6但是题目说了是1到9，是不带0的，所以只有1113或1122排列，总共4+6=10种


　　是1-9里面选四个加起来等于6，可以是1+1+1+3或者1+1+2+2，排列可以换


　　1113 1131 1311 3111


　　1122 1212 1221 2112 2121 2211


　　所以总共就是十种，我也不造为什么之前的构筑做出来是24……