【简答题】设X 1 ,X 2 ,X 3 相互独立.且X 1 ~U[0,6],X 2 ~N(0,4),X 3 ~P(2),Y=X 1 -2X 2 +3X 3 ,求EY及DY.
【简答题】(1)设函数f(x)=xlnx+(1-x)ln(1-x)(0<x<1),求f(x)的最小值; (2)设正数 p 1 , p 2 , p 3 ,…, p 2 n 满足 p 1 + p 2 + p 3 +…+ p 2 n =1,求证: p 1 ln p 1 + p 2 ln p 2 + p 3 ln p 3 +…+ p 2 n ln p 2 n ≥-n.
【单选题】William Faulkner was the writer of .
C.
The Sound and the Fury
【简答题】(1) 设随机变量X 1 ,X 2 ,X 3 相互独立,且有 ,求P{X 1 =2,X 2 =2,X 3 =5),E(X 1 X 2 X 3 ),E(X 1 -X 2 ),E(X 1 -2X 2 ). (2) 设X,Y是随机变量,且有E(X)=3,E(Y)=1,D(X)=4,D(Y)=9,令Z=5X-Y+15,分别在下列3种情况下求E(Z)和D(Z). (i) X,Y相互独立,(ii)X,Y不相关...
【判断题】The writer of Walden is Henry David Thoreau.()
【简答题】The writer has a high opinion of Thoreau's living all by himself at Walden Pond.
【判断题】The writer of Walden is Henry David Thoreau.
【简答题】设X~N(3,2 2 ),(1)求P{2<X≤5),P{-4<X≤10),P{|X|>2),P{X>3);(2)确定c使得P{X>c}=P{X≤c};(3)设d满足P{X>d}≥0.9,问d至多是多少?