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  1. M

    Adding random variables

    Hello, i need some help with an assignment. we have two random variables x1 and x2. E[x1]=E[X2]=1, VAR[X1]=4 and VAR[X2]=5. Y=1/3(3X1-6X2) Find VAR[Y], I think I have to just do this: 1/3(3*VAR[X1]+6*VAR[X2]) and get: 1/3(3*4+6*5)=14 EDIT: COV[X,Y]=1 Can anyone confirm or explain my...
  2. M

    Adding random variables

    Hello, i need some help with an assignment. we have two random variables x1 and x2. E[x1]=E[X2]=1, VAR[X1]=4 and VAR[X2]=5. Y=1/3(3X1-6X2) Find VAR[Y], I think I have to just do this: 1/3(3*VAR[X1]+6*VAR[X2]) and get: 1/3(3*4+6*5)=14 Can anyone confirm or explain my mistake if it's wrong...