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 274.   一个给了个图表,     选课了人数          没选课人数            总人数             男                                                       18             女             合计           26 求总人数~ 条件2说女生总数是没选人数总数的两倍,这个可以直接推出 貌似不可以了  
 楼主: 这题是可以解的: 原题管22-Q32: |  | Number Studying Biology | Number Not Studying Biology | Total  |  |  |  | Number of Boys |        15 |         3 | 18  |  |  |  | Number of Girls |         |          |   2X |  |  |  | Total  | 26  |         X |    | 
   The table above shows the number of students in a certain high school class who are boys and the number of students in the class who are studying biology.  What is the total number of students in the class? (1) Of the boys in the class, 15 are studying biology. See bule (2) The number of girls in the class is twice the number of students in the class who are not studying biology.     26+x=18+2x è X=8 è total number of students = 26+8 = 34 (充分) 答案是B |