I'm expecting to see this question on my calc exam but am not sure how to solve it. The rate R, at which people become sick during an epidemic of the...

I'm expecting to see this question on my calc exam but am not sure how to solve it.

The rate R, at which people become sick during an epidemic of the flu is given by R(t)=1000te^0.4t people/day, since the start of the epidemic (t=0). Find the total number of people that get sick after a long period of time?