※ 引述《domeself (be strong)》之銘言： : Q19 : In a certain region, the number of children who have been vaccinated : against rubella is twice the number who have been vaccinated against : mumps. The number who have been vaccinated against both is twice the : number who have been vaccinated only against mumps. If 5,000 have been : vaccinated against both, how many have been vaccinated only against : rubella? : A.2,500 : B.7,500 : C.10,000 : D.15,000 : E.17,500 : ANS:C : Thanks. 第一次在gmat板上po文 我試解一下 不知道說不說得清楚 原題意為 有接種過Rubella(德國麻疹)疫苗的小孩數目是有接種過Mumps(腮腺炎)的小孩數目的兩倍 將代數式設為 R=2M 另外，題又說 兩種疫苗都有接種過的小孩數目是只接種過mumps小孩數的兩倍 將兩種疫苗都有接種過的小孩數目設為X 則此句話的代數式為 X=2(M-X) 題目並告訴我們 兩種疫苗都有接種過的小孩數目為5000 將5000代入第二式X中 可求出M=7500 再將M=7500代入一式中 可求出R=15000 但最後要小心 題目問的是只接種過Rubella疫苗小孩的數量 所以還要將R-X=15000-5000=10000 才是答案喔!! --

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