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Drink H · 2020年01月19日

问一道题:NO.PZ2020010304000035 [ FRM I ]

问题如下图:

答案d,方差=(b-a)^2=12中,“12”是怎么来的?

2 个答案

tetexe · 2020年02月20日

12哪里来的呢

orange品职答疑助手 · 2020年02月21日

这是通过积分算它的方差时,产生的常数项

任会会 · 2020年03月13日

能详细解答下12的由来吗?积分如何计算产生的12?有演示吗

orange品职答疑助手 · 2020年01月19日

同学你好,这个是除号,而不是等号。服从均匀分布(a,b)的随机变量X的方差是 (b-a)^2/12,这个是通过积分的计算推导出来的,这是它的方差公式

🍥 · 2020年05月19日

还是没明白12如何得出 可以详细解答一下吗

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NO.PZ2020010304000035问题如下experiment yiel the following tIt is hypothesizeththe ta comes from a uniform tribution, U(0, b). Calculate the sample meanvariance. Whare the unbiaseestimators of the meanvariance?Calculate the b in U(0, using the formula for the meof a uniform stribution anthe value of the unbiasesample mefounin part b. Calculate the b in U(0, using the formula for the varianof a uniform stribution anthe value of the unbiasesample varianfounin part b.Use the stanrformuto get the sample variance(here, n=15)μ=n−1∑i=1nXi=0.39\mu = n^{-1}\sum_{i=1}^{n}X_i =0.39μ=n−1∑i=1n​Xi​=0.39σ2=n−1∑i=1n(Xi−μ)2=0.08\sigma^2 = n^{-1}\sum_{i=1}^{n}{(X_i-\mu)}^2 =0.08σ2=n−1∑i=1n​(Xi​−μ)2=0.08b.The sample meis alrea unbiaseFor the variance:s2=nσ2/(n−1)=15∗0.080/14=0.086s^2=n\sigma^2/(n-1) =15*0.080/14=0.086s2=nσ2/(n−1)=15∗0.080/14=0.086c.The mefor a U(a,stribution is given as: μ=(a+b)/20.385=(0+b)/2b=0.77 The varianfor a U(a,stribution is given as: σ2=(b−a)2/12\sigma^2=(b-a)^2/12σ2=(b−a)2/120.086=b2/120.086=b^2/120.086=b2/12b=1.016b=1.016b=1.016老师您看我写的不明白的地方总体方差不应该是(样本方差的均值*15)/14吗?

2024-05-13 15:24 1 · 回答

NO.PZ2020010304000035 问题如下 experiment yiel the following tIt is hypothesizeththe ta comes from a uniform tribution, U(0, b). Calculate the sample meanvariance. Whare the unbiaseestimators of the meanvariance?Calculate the b in U(0, using the formula for the meof a uniform stribution anthe value of the unbiasesample mefounin part b. Calculate the b in U(0, using the formula for the varianof a uniform stribution anthe value of the unbiasesample varianfounin part Use the stanrformuto get the sample variance(here, n=15)μ=n−1∑i=1nXi=0.39\mu = n^{-1}\sum_{i=1}^{n}X_i =0.39μ=n−1∑i=1n​Xi​=0.39σ2=n−1∑i=1n(Xi−μ)2=0.08\sigma^2 = n^{-1}\sum_{i=1}^{n}{(X_i-\mu)}^2 =0.08σ2=n−1∑i=1n​(Xi​−μ)2=0.08b.The sample meis alrea unbiaseFor the variance:s2=nσ2/(n−1)=15∗0.080/14=0.086s^2=n\sigma^2/(n-1) =15*0.080/14=0.086s2=nσ2/(n−1)=15∗0.080/14=0.086c.The mefor a U(a,stribution is given as: μ=(a+b)/20.385=(0+b)/2b=0.77 The varianfor a U(a,stribution is given as: σ2=(b−a)2/12\sigma^2=(b-a)^2/12σ2=(b−a)2/120.086=b2/120.086=b^2/120.086=b2/12b=1.016b=1.016b=1.016 总体是Uniform的话,样本一定是uniform吗?如果是的话,可以用(0.95-0)/2来计算样本均值吗

2024-04-23 10:51 1 · 回答

NO.PZ2020010304000035问题如下experiment yiel the following tIt is hypothesizeththe ta comes from a uniform tribution, U(0, b). Calculate the sample meanvariance. Whare the unbiaseestimators of the meanvariance?Calculate the b in U(0, using the formula for the meof a uniform stribution anthe value of the unbiasesample mefounin part b. Calculate the b in U(0, using the formula for the varianof a uniform stribution anthe value of the unbiasesample varianfounin part b.Use the stanrformuto get the sample variance(here, n=15)μ=n−1∑i=1nXi=0.39\mu = n^{-1}\sum_{i=1}^{n}X_i =0.39μ=n−1∑i=1n​Xi​=0.39σ2=n−1∑i=1n(Xi−μ)2=0.08\sigma^2 = n^{-1}\sum_{i=1}^{n}{(X_i-\mu)}^2 =0.08σ2=n−1∑i=1n​(Xi​−μ)2=0.08b.The sample meis alrea unbiaseFor the variance:s2=nσ2/(n−1)=15∗0.080/14=0.086s^2=n\sigma^2/(n-1) =15*0.080/14=0.086s2=nσ2/(n−1)=15∗0.080/14=0.086c.The mefor a U(a,stribution is given as: μ=(a+b)/20.385=(0+b)/2b=0.77 The varianfor a U(a,stribution is given as: σ2=(b−a)2/12\sigma^2=(b-a)^2/12σ2=(b−a)2/120.086=b2/120.086=b^2/120.086=b2/12b=1.016b=1.016b=1.016样本均值应等于A加B然后除以2;无偏均值就是该均值。样本方差等于B减去A 平方然后除以12。解题公式不知道什么意思。最后两问不知道在说什么。均匀分布到底应该怎么计算?谢谢。尤其是最后两个问题在说什么。感觉均匀分布前提和适用场景特别不清楚。烦请详细说明,谢谢

2023-03-26 06:04 1 · 回答

NO.PZ2020010304000035问题如下 experiment yiel the following tIt is hypothesizeththe ta comes from a uniform tribution, U(0, b). Calculate the sample meanvariance. Whare the unbiaseestimators of the meanvariance?Calculate the b in U(0, using the formula for the meof a uniform stribution anthe value of the unbiasesample mefounin part b. Calculate the b in U(0, using the formula for the varianof a uniform stribution anthe value of the unbiasesample varianfounin part b.Use the stanrformuto get the sample variance(here, n=15)μ=n−1∑i=1nXi=0.39\mu = n^{-1}\sum_{i=1}^{n}X_i =0.39μ=n−1∑i=1n​Xi​=0.39σ2=n−1∑i=1n(Xi−μ)2=0.08\sigma^2 = n^{-1}\sum_{i=1}^{n}{(X_i-\mu)}^2 =0.08σ2=n−1∑i=1n​(Xi​−μ)2=0.08b.The sample meis alrea unbiaseFor the variance:s2=nσ2/(n−1)=15∗0.080/14=0.086s^2=n\sigma^2/(n-1) =15*0.080/14=0.086s2=nσ2/(n−1)=15∗0.080/14=0.086c.The mefor a U(a,stribution is given as: μ=(a+b)/20.385=(0+b)/2b=0.77 The varianfor a U(a,stribution is given as: σ2=(b−a)2/12\sigma^2=(b-a)^2/12σ2=(b−a)2/120.086=b2/120.086=b^2/120.086=b2/12b=1.016b=1.016b=1.016​a求的是sample variance,为什么分母不是除以n-1 呢?

2023-01-25 17:16 1 · 回答

NO.PZ2020010304000035问题如下experiment yiel the following tIt is hypothesizeththe ta comes from a uniform tribution, U(0, b). Calculate the sample meanvariance. Whare the unbiaseestimators of the meanvariance?Calculate the b in U(0, using the formula for the meof a uniform stribution anthe value of the unbiasesample mefounin part b. Calculate the b in U(0, using the formula for the varianof a uniform stribution anthe value of the unbiasesample varianfounin part b.Use the stanrformuto get the sample variance(here, n=15)μ=n−1∑i=1nXi=0.39\mu = n^{-1}\sum_{i=1}^{n}X_i =0.39μ=n−1∑i=1n​Xi​=0.39σ2=n−1∑i=1n(Xi−μ)2=0.08\sigma^2 = n^{-1}\sum_{i=1}^{n}{(X_i-\mu)}^2 =0.08σ2=n−1∑i=1n​(Xi​−μ)2=0.08b.The sample meis alrea unbiaseFor the variance:s2=nσ2/(n−1)=15∗0.080/14=0.086s^2=n\sigma^2/(n-1) =15*0.080/14=0.086s2=nσ2/(n−1)=15∗0.080/14=0.086c.The mefor a U(a,stribution is given as: μ=(a+b)/20.385=(0+b)/2b=0.77 The varianfor a U(a,stribution is given as: σ2=(b−a)2/12\sigma^2=(b-a)^2/12σ2=(b−a)2/120.086=b2/120.086=b^2/120.086=b2/12b=1.016b=1.016b=1.016第三问和第四问求具体解析及教程是哪一页有讲到啊?

2022-09-25 14:36 1 · 回答