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1996年中考题中的应用题,形式多样,新老结合,丰富多彩。下面以一些典型试题为例,介绍其解题技巧。 1.浓度问题 中考中的“浓度问题”多以“混合溶液”形式出现。解此类应用题时,列方程一般应以“物质的纯量”或“水含量”两种方法之一进行。 例1.一桶中装满浓度为20％的盐水40千克,若倒出一部分盐水后,再加入一部分水,倒入水的重量是倒出盐水重量的一半,此时盐水的浓度是15％,求倒出盐水多少千克?
In 1996, the questions in the application for the examination were varied, and the combination of old and new was rich and colorful. Here are some typical questions as an example to introduce their problem-solving skills. 1. Concentration issues The “concentration problems” in the examinations are mostly in the form of “mixed solutions”. When solving such applications, the equations should generally be performed in one of two ways: “the net amount of material” or “the water content.” Example 1. A bucket is filled with 40 kg of brine with a concentration of 20%. If a portion of the brine is poured, a portion of the water is added. The weight of the poured water is half of the weight of the poured brine, and the concentration of the brine is 15%. How many kilograms of salt water should be poured out?