Find the sum of this series:
$$ \sum_{n=1}^\infty \frac{n}{(n+1)!} $$
I'm really struggling with this one.. Any help will be highly appreciated. Thanks you.
This is my first time tackling this kind of problem.
1. Let $Q$ be the percentage of what he remembers.
2. Let $t$ be the time in weeks.
3. Initial condition 1: $Q=0.95 $ and $t=0$
5. Initial condition 2: $Q=0.80 $ and $t=1$
Now I'm stuck about finding the rate. From what I understand...