1
For the mean, you can apply the linearity of expectation a bit more aggressively than you do: since this is just a finite sum we know we can exchange expectation and summation so
$$
\text E\left(\sum_{ij} Y_{ij}\right) = \sum_{ij} \text E Y_{ij} = nt\mu
$$
and then $\text E \bar Y_{++}$ follows.
For the variance, the key step is remembering that the random ...
Only top voted, non community-wiki answers of a minimum length are eligible
