In: Statistics and Probability
Let X and Y be independent random variables with mean πX and ππ, and variances ππ 2 and ππ 2 respectively. Show that
πππ[π β π] = ππ 2 β ππ 2 + ππ 2 β ππ 2 + ππ 2 β ππ 2
GIVEN:
Let X and Y be independent random variables with mean and , and variances and respectively.
TO PROVE:
PROOF:
Given the mean of X
Variance of X
The formula for variance is given by,
Given the mean of Y
Variance of Y
The formula for variance is given by,
Thus we have ; ; ; ; and .
First, we compute the mean of XY,
{Since X and Y are independent.}
Β Β
Now the formula for variance of XY is given by,
{Since X and Y are independent and .}
Β Β
Using and , we obtain the result,
Thus .