题目

Half of a large pizza is cut into 4 equal-sized pieces, and the other half is cut into 6 equal-sized pieces. If a person were to eat 1 of the larger pieces and 2 of the smaller pieces, what fraction of the pizza would remain uneaten?


选项

A.

B.

C.

D.

E.

解析

另一种方法——只用分数计算。把披萨看作整体1,先暂时放一边,最后再用。 1)把披萨的\(\frac{1}{2}\)切成4等份 每块新切的披萨大小为:\(\frac{(\frac{1}{2})}{4} = \frac{1}{8}\) 2)把披萨的另一部分\(\frac{1}{2}\)切成6等份 每块新切的披萨大小为:\(\frac{(\frac{1}{2})}{6} = \frac{1}{12}\) 3)吃掉1块大份和2块小份 吃掉的总量:\((\frac{1}{8} + \frac{2}{12}) = (\frac{3}{24} + \frac{4}{24}) = \frac{7}{24}\) 以分母为“整体1”的基准,披萨(\(=1 = \frac{24}{24}\)) 4)没吃掉的总量: \((\frac{24}{24} - \frac{7}{24}) = \frac{17}{24}\) 答案:E *注:\(\frac{1}{2}\)平均切分=“除以”4:\(\frac{(\frac{1}{2})}{4}\)。该式中除数4的隐含分母是1,即\(\frac{(\frac{1}{2})}{(\frac{4}{1})}\)……取倒数后相乘。
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