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Normal Random Variables Question

by Onetimeuser
Tags: normal, random, variables
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Onetimeuser
#1
May29-10, 10:58 PM
P: 2
1. The problem statement, all variables and given/known data

Problem 1 – Normal Random Variables

B) Y ~ N(300, 100). Pr (300 < Y < 320) = 0.4772

D) H ~ N(4000, 25). R = f(H) = 0.5H – 60. E(R) = 1940; Var(R) = 156.25





I have a problem solving these problems above...I missed the class when we covered this subject and now I am lost upon solving them.. I hope somebody can help, thanks a lot
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statdad
#2
May30-10, 09:12 AM
HW Helper
P: 1,361
For a normally distributed random variable,

[tex]
P(a < X < b) = P(X < b) - P(X < a)
[/tex]

For any random variable [itex] W [/itex], if [itex] a, b [/itex] are real numbers,
and

[tex]
Z = aW + b
[/tex]

then

[tex]
E(Z) = aE(W) + b, \quad Var(Z) = a^2 Var(W)
[/tex]

(as long as the mean and variance of [itex] W [/itex] exist)
Onetimeuser
#3
May31-10, 11:34 AM
P: 2
Thanks for the reply!!

However, when I plug it in I dnt get the right answer.... did u check if the given answer is right?


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