If the mean of the frequency distribution

is 28, then its variance is __________.

Let the mean and variance of 8 numbers $$x, y, 10,12,6,12,4,8$$ be $$9$$ and $$9.25$$ respectively. If $$x > y$$, then $$3 x-2 y$$ is equal to _____________.

If the mean and variance of the frequency distribution

are 9 and 15.08 respectively, then the value of $$\alpha^2+\beta^2-\alpha\beta$$ is ___________.

If the variance of the frequency distribution

is 3, then $$\alpha$$ is equal to _____________.