时材料的电导率最小,并求σmin的表达式
①证明当μ。≠ μ,且电子浓度=(n)_(i)sqrt ({u)_(p)/(u)_(n)}, =(n)_(1)sqrt ({mu )_(n)/(mu )_(p)
(B) dfrac (sqrt {n)(overline (X)-mu )}(S)sim t(n-1).-|||-(C) dfrac (sqrt {n)(ove
设随机变量 xi sim N(mu,36),eta sim N(mu,64),记 p_(1)=P(xi leq mu-6),p_(2)=P(eta geq mu
A approx N(mu ,1).Bapprox N(mu ,1).C approx N(mu ,1).D approx N(mu ,1).设总体其中未知,如
X sim N(mu, 4^2), Y sim N(mu, 5^2), p_1 = PX leq mu - 4, p_2 = PY geq mu + 5, 则(
设总体approx N(mu ,(1)^2) , approx N(mu ,(1)^2)是来自 approx N(mu ,(1)^2)的样本,则approx N
(sim N(mu ,(sigma )^2),sim N(mu ,(sigma )^2),sim N(mu ,(sigma )^2),sim N(mu ,(si
设 X_1, X_2, ..., X_n 是来自正态总体 X sim N(mu, sigma^2) 的样本,则 (overline(X) - mu)/(sqrt
12.证明lim_(ntoinfty)((1)/(sqrt(n^2)+1)+(1)/(sqrt(n^2)+2)+...+(1)/(sqrt(n^2)+n))=1
设随机变量 X 和 Y 均服从正态分布,X sim N(mu, 4^2),Y sim N(mu, 5^2),而 p_1 = P(X leq mu - 4),p_