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IMAGINE, THINK, and DO
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--- S. Muthu Muthukrishnan

Local Notes

Local Notes 是一款 Windows 下的笔记系统.

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Sowya

Sowya 是一款运行于 Windows 下的计算软件.

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注: 自 v0.550 开始, Calculator 更名为 Sowya. [Sowya] 是吴语中数学的发音, 可在 cn.bing.com/translator 中输入 Sowya, 聆听其英语发音或法语发音.





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Problèmes d'affichage aléatoires

概率统计 >> 概率论
Questions in category: 概率论 (Probability).

[Exer13-3] Exercise 71 of Book {Devore2017B} P.184

Posted by haifeng on 2020-05-13 09:51:06 last update 2020-05-18 06:25:57 | Answers (1)


Let $X$= the hourly median power (in decibels (分贝/décibels/Dezibel)) of received radio signals transmitted between two cities. The authors of the article "Families of Distributions for Hourly Median Power and Instantaneous Power of Received Radio Signals" (J. Research National Bureau of Standards, vol. 67D, 1963: 753--762) argue that the lognormal distribution provides a reasonable probability model for $X$. If the parameter values are $\mu=3.5$ and $\sigma=1.2$, calculate the following:

  • (a) The mean value and standard deviation of received power
  • (b) The probability that received power is between $50$ and $250$ dB.
  • (c) The probability that $X$ is less than its mean value. Why is this probability not $.5$?