Can you correctly write paragraph?

Can a teacher correctly write the paragraph please so it is clear and nice without changing it very much?

We tell customers that there is a 3 week wait even though the wait can range anywhere between 10 and 20 days just to be on the safe side we say 3 weeks. We don't know how long it take the department to go through applications or how many applications they go through a day. It depends on the number of applications they go through a day and the speed at which they go through applications.