The following data sufficiency problems consist of a question and two statements

游客2024-01-14  19

问题 The following data sufficiency problems consist of a question and two statements, labeled (1) and (2), in which certain data are given. You have to decide whether the data given in the statements are sufficient for answering the question. Using the data given in the statements plus your knowledge of mathematics and everyday facts (such as the number of days in July or the meaning of counterclockwise), you must indicate whether
   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. [br] If 5a=9b=15c, what is the value of a+b+c?
   (1) 3c-a=5c-3b
   (2) 6cb=10a

选项

答案 B

解析 Statement (1) alone is insufficient; you can restate the equation as 3b=2c+a; if you multiply both sides of the equation by 3, you get 9b=6c+3a; you can determine from the equation 5a=15c that a=3c, so all this restated equation tells you is that 9b=15c=5a, which tells you nothing about the actual value of a or b. Statement (2) is sufficient. If you divide both sides of the equation by 2, you get 3cb=5a; you know that 5a=9b, so you can form the equation 3cb=9b, which you can reduce to c=3. With this value you can determine that a=9 and b=5, and you can thereby find a definitive answer to the question posed.
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