求助数学题。。完全看不懂，从题目到答案。。求大神！！

灵狩Icy · 发表于 2015-5-19 16:37:41

A spirit and water solution is sold in a market. The cost per liter of the solution is directlyproportional to the part (fraction) of spirit (by volume) the solution has. A solution of 1 liter of spiritand 1 liter of water costs 50 cents. How many cents does a solution of 1 liter of spirit and 2 liters ofwater cost?

答案是50.。这样写的：
Since the cost of each liter of the spirit water solution is directly proportionally to the part (fraction) ofspirit the solution has, the cost per liter can be expressed as kf, where f is the fraction (part of) of pure spiritthe solution has.
Now, each liter of the m liters of the solution containing n liters of the spirit (f = n/m) should cost kf =k(n/m). The m liters cost m • k(n/m) = kn. Hence, the solution is only priced for the content of the spirit thesolution has (n here). Hence, the cost of the two samples given in the problem must be the same since bothhave exactly 1 liter of spirit. Hence, the answer is (C), 50 cents.

看不懂。。求翻译+详解

不如前 · 发表于 2015-5-19 17:49:10

翻译：超市卖烈酒和水的混合溶液，每升溶液的价格和（酒/溶液）成正比，含1L水和1L酒的溶液50块，问含2L水和1L酒的溶液多少钱？
解释：
因为每升溶液的价格和（酒/溶液）成正比，所以设比例系数是k，设酒/溶液=f，每升价格=kf
假设m升溶液含n升酒，f=n/m，每升价格=k*n/m，所以m升的价格是kn，由此可以看出溶液的价格只和酒精体积的多少有关，因为含1L酒的价格是50，所以无论加多少水都是50块

飞越马德里 · 发表于 2015-5-19 17:49:35

就是市场上在卖一种溶液，价格是由这个spirit的含量决定的。一份溶液有1升spirit和1升水构成，卖50，现在一份溶液由1升spirit和2升水构成，卖多少？
因为都只有1升spirit，所以都是50。。。。但愿没有误人子弟。

灵狩Icy · 发表于 2015-5-19 20:56:26

不如前发表于 2015-5-19 17:49
翻译：超市卖烈酒和水的混合溶液，每升溶液的价格和（酒/溶液）成正比，含1L水和1L酒的溶液50块，问含2L水 ...

谢谢！！另外又有不会的题了！！
http://forum.chasedream.com/foru ... ;extra=#pid21762619

灵狩Icy · 发表于 2015-5-19 20:57:01

飞越马德里发表于 2015-5-19 17:49
就是市场上在卖一种溶液，价格是由这个spirit的含量决定的。一份溶液有1升spirit和1升水构成，卖50，现在一 ...

明白啦！！谢谢！！！

[考古] 求助数学题。。完全看不懂，从题目到答案。。求大神！！

所属分类: GMAT考试

正在浏览此版块的会员 ()

浏览过的版块