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有些分数或者比的问题,直接列式解答会有一定的难度,它们的数量关系可以转化成“份数”关系,用这种方法可以简化思路,令人耳目一新。例1:一个桶里盛2/5的油漆,连桶共重3千克,如果盛了3/5的油漆,那么连桶共重4.2千克,这个桶重多少千克?【分析与解答】我们把这个桶看成5份,盛2份油漆连桶重3千克,盛3份油漆连桶重4.2千克,那么4.2—3就得到1份的油漆重1.2千克。3千克中包含着2份的油漆和空桶,所以空桶的重量为:3—1.2×2=0.6(千克)
There are some problems with scores or ratios, and there is a certain degree of difficulty in direct column solutions. The quantitative relationship between them can be converted into “number of copies ” relationship. This method can be used to simplify the thinking and refreshing. Example 1: A barrel filled with 2/5 of paint, with a total weight of 3 kg barrel, if filled with 3/5 of paint, so even a total weight of 4.2 kg bucket, how many kg of this bucket? [Analysis and Answers] We put This barrel is considered as 5 parts, 2 pieces of paint with a barrel weighs 3 kg and 3 parts of paint weighs 4.2 kg, then 4.2-3 gets 1 part with 1.2 kg of paint. 3 kg contains 2 parts of paint and empty bucket, so empty bucket weight is: 3-1.2 × 2 = 0.6 (kg)