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问题 问答题 简答题

描述集中趋势的指标有哪些？其适用范围有何异同？

答案

参考答案：

均数：正态或近似正态分布

几何均数：等比数列或对数正态分布资料

中位数：资料是偏态分布的；分布不规则；一端或两端有不确定数据（开口资料）时。

问答题 简答题

铁路交通事故主要有哪两类（条例的适用范围）？
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单项选择题

Electrical engineers have repeatedly demonstrated that the best solid-state amplifiers are indistinguishable from the best vacuum-tube amplifiers with respect to the characteristics commonly measured in evaluating the quality of an amplifier’s musical reproduction. Therefore, those music lovers who insist that recorded music sounds better when played with the best vacuum-tube amplifier than when played with the best solid-state amplifier must be imagining the difference in quality that they claim to bear.
Which one of the following, if true, most seriously weakens the argument

A．Many people cannot tell from listening to it whether a recording is being played with a very good solid-state amplifier or a very good vacuum-tube amplifier.

B．The range of variation with respect to the quality of musical reproduction is greater for vacuum-tube amplifiers than for solid-state amplifiers.

C．Some of the characteristics that are important in determining how music sounds to a listener cannot be measured.

D．Solid-state amplifiers are more compact, use less power, and generate less heat than vacuum-tube amplifiers that produce a comparable volume of sound.

E．(E) Some vacuum-tube amplifiers are clearly superior to some solid-state amplifiers with respect to the characteristics commonly measured in the laboratory to evaluate the quality of an amplifier’s musical reproduction.
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