I've been doing this but not getting this answer. Can anyone guide me to right answer?
Let X be the number obtained when one true die is tossed. Let T be the sum of numbers obtained when X true dice are then thrown. Calculate $\mathbb{E}[T]$ and $Var[T]$.
Right answers are:
$$\mathbb{E}[T] = \frac{49}{4}$$ $$Var[T] = \frac{735}{16}$$