I am trying to compute, until now with no luck, the variance of $$ \sum_{y=1}^n{ A*(1+r)^{y} } $$ which is equivalent to
$\frac{(1+r)[(1+r)^{y}-1]}{r}*A$,
Where we assume $$ r \sim N(\mu,\sigma^2)$$
A is a constant.
Thanks
EDIT :
Following @Zen, we could approximate $$\mathrm{Var}(FV)≈\sigma^2\times(g′(μ))^2.$$