If X1, X2, and X3 are independent and have the means 4, 9, and 3 and the vaiance 3,7, and 5, find the mean and the variance of:

a. Y = 2X1 -3X2 +4X3

b. Z = X1 -2X2 -X3

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- May 17th 2008, 09:45 AMhaleyGeorgemean and variance
If X1, X2, and X3 are independent and have the means 4, 9, and 3 and the vaiance 3,7, and 5, find the mean and the variance of:

a. Y = 2X1 -3X2 +4X3

b. Z = X1 -2X2 -X3 - May 17th 2008, 09:50 AMMoo
- May 21st 2008, 12:50 PMhaleyGeorge
I know this is probably a really stupid question, but do I just plug in the numbers given for mean and variance into the equation? Or what is my next step?

- May 21st 2008, 12:51 PMMoo
- May 21st 2008, 01:17 PMhaleyGeorge
ok, then for the first one I got E(Y) = -7 and var(Y) = 155. Is that correct? Thanks for all your help!

- May 21st 2008, 01:23 PMMoo
- May 21st 2008, 01:31 PMhaleyGeorge
E(Z) = -17 and var(Z) = 36