Abstract: This paper discusses the test problem concerning ratios of two normal density functions.

摘要：本文讨论对两样本正态分布密度比的假设检验。

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The experiment shows: the change of the velocity of sound through normal density alit is regular and directly proportional to the strength of alit;

结果表明：在正常密度水泥石实验中一般声速反应较规则，基本与强度正相关；

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The bolls per unit area of cotton leafy shoots retained at low density could reach the same level as cotton leafy shoots removed at normal density.

低密度下留叶枝单位面积成铃可以达到高密度下不留叶枝的水平。

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In fact, they tend to be pretty sick, as the normal thinning from fires is suppressed, resulting in an unhealthy tree density, invasion and death from bark beetles, and then surprise a mega fire that takes down the entire woods.

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At 220 pixels-per-inch, the Retina display's pixel density is so high the human eye cannot distinguish individual pixels from a normal viewing distance, so text and graphics look incredibly sharp.

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