SAT官方每日一题：2011年8月23日

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　　2011年8月23日

　　考试类型:Mathematics > Standard Multiple Choice

　　Read the following SAT test question and then click on a button to select your answer. 

　　In an solution of water and alcohol, the ratio by mass of water to alcohol is to . If grams of a solution consisting of grams water for each gram of alcohol is added to the solution, what fraction by mass of the new solution is alcohol?

　　A.

　　B.

　　C.

　　D.

　　E.

　　正确答案:B

　　解析:

　　To find what fraction by mass of the new solution is alcohol, you can find how many grams of alcohol are in the final solution of grams. Since the solution is part alcohol to parts water, it is alcohol. So it contains grams of alcohol. Similarly, the solution is alcohol by mass, so it contains grams of alcohol. Thus, the final 20-gram solution contains grams of alcohol, so , or , of it is alcohol.