mean and standard deviation of discrete variable

ka923

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the number of points issac scores for collecting treasures is Y
Y=100X-50
i have drawn a table and calculated E(X) and Var(X) of the original table
Calculate the mean and the standard deviation of Y
 
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the number of points issac scores for collecting treasures is Y
Y=100X-50
i have drawn a table and calculated E(X) and Var(X) of the original table
Calculate the mean and the standard deviation of Y
Does that mean you have calculated E(X) and Var(X)?
If so, how are they related to the mean and the standard deviation of Y?
The answer depends upon the properties of E(100X-50) & Var(100X-50).
 
yes, so do i just sub in the value of var(x) for the standard deviation?
also i thought E(X) was already the mean
 
yes, so do i just sub in the value of var(x) for the standard deviation?
also i thought E(X) was already the mean
Well, what does your notes/eextbook have to szay about this?
Do you see that \(\displaystyle E(\alpha X+\beta Y)=\alpha E( X)+\beta E( Y)~?\)

Do you know that \(\displaystyle Var(X)=E[(X-\mu)^2]=E(X^2)-\mu^2~?\)

 
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