Sure, let's work through this problem step by step.
1. We first note that one book weights 0.65 kg.
2. Then, we know that there are 5 copies of the book in the box.
3. To find the total weight of all the books in the box, we should multiply the weight of one book by the number of copies.
4. So, we do 0.65 kg (the weight of one book) multiplied by 5 (the number of copies).
5. This multiplication gives us 3.25 kg.
Therefore, the total weight of the books in the box is
Answer: 3.25 kg.