Let $\rm \Sigma_{i=1}^9x_i^2=885$ If M is the mean and σ is the standard deviation of  x₁, x₂, x₃.....x₉ then what is the value of M² + σ²?

The mean of the series x₁, x₂...x_n is x̅ If x_n is replaced by k, then what is the new mean?

If two random variables $X$ and $Y$ are connected by relation $\frac{2 X-3 Y}{5 X+4 Y}=4$ and $X$ follows Binomial distribution with parameters $n=10$ and $p=\frac{1}{2}$, then what is the variance of $Y$ ?