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R version 2.11.1 (2010-05-31)Copyright (C) 2010 The R Foundation for Statistical ComputingISBN 3-900051-07-0

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> library(BSDA)Error in library(BSDA) : there is no package called 'BSDA'> utils:::menuInstallPkgs()--- Please select a CRAN mirror for use in this session ---Error in contrib.url(repos, type) :

trying to use CRAN without setting a mirrorIn addition: Warning message:In open.connection(con, "r") : unable to resolve 'cran.r-project.org'> #phan phoi lien tuc> #1. phan phoi chuan> #neu X~N(nu, sima^2)> #P(X=a)=0> #P(X #P(X=a)=P(X>a)=1-pmorm(a,mu,sigma)> #P(a #ham qnorm la ham nguoc cua ham pnorm

> #cho truoc mot cai xac suat la p0> # tim a sao cho P(X #a=qnorm(p0,mu,sigma)>> #tim asao cho P(x>a)=p0> # a=pnorm(1-p0,mu,sigma)> # a=qnorm(1-p0,mu,sigma) dung>>> #2. phan phoi mu> # neu X~exp(lamda)> #P(X #P(X>a)=1-pexp(a,lamda)

> #P(a # bai tap> # bai 41> #cho X~N(8,5)> #a. P(X>5)> 1-pnorm(5,8,5)[1] 0.7257469>> #b.P(2

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> pnorm(6,8,5)-pnorm(2,8,5)[1] 0.2295086>> #tim Xo sao cho P(X #tim Xo sao cho P(X qnorm(0.4,8,5)[1] 6.733264> #tim Xo sao cho P(X>Xo)=0.8> qnorm(1-o.8,8,5)Error in qnorm(1 - o.8, 8, 5) : object 'o.8' not found> qnorm(1-0.8,8,5)[1] 3.791894>> #bai 44> qnorm(1-0.1,100,14.2)[1] 118.1980> #theo bai ta co X~N(100,14.2)> # goi a la chi so IQ thap nhat trong nhom 10% nhung nguoi co chi so IQ cao nhat the gioi> #a la gia tri de P(X>a)=10%> qnorm(1-0.1,100,14,2)[1] 117.9417> qnorm(1-0.1,100,14.2)[1] 118.1980

> #bai 42> #GOI X la so nam trong 4 nam co luong mua khong qia 1600> #X tuan theo phan phoi nhi thuc voi n=4,p=?> #trong do P la xac suat de luong mua trong nam khong qua 1600> # goi Y bnn chi luong mua trong 1 nam,Y~N(1800,100)> #p=P(Y p=pnorm(1600,1800,100)> p[1] 0.02275013> # vay xac suat de co 2 trong 4 nam co luong mua khong qua 1600> #P(x=2)> #X~B(n=4,p)va bang ham dbinom(2,4,p)> dbinom(2,4,p)

[1] 0.002965721>> > #bai 45> # goi X la so dam ma mot chiec oto di duoc cho den hong> # X~EXP( lamda=1/20)> # trung binh mot 0 to di duoc 20 dam thi hong> #1. tinh kha nang ma mua mot oto moi ma di duoc 20 dam> #2. tinh kha nang mua oto cu ma da di 10dam cho toi khi di duoc 20dam> #1. P(x>20)> 1-pexp(20,1/20)[1] 0.3678794> #2.P(X>=30|x>10)> (1-pexp(30,1/20))/(1-pexp(10,1/20))

[1] 0.3678794>