Every copywriter can create a limited number of copies in a week or so. If I ask you how many copies you can make, you might give me a big number to create an impression and increase the chances of securing the position. You should remember that they are looking for a person who can create quality copies instead of several low-quality ones. You can stretch your limits and give them a considerable number, but to maintain the quality, you need to provide an appropriate number that only needs a little stretching on your behalf. For instance, you can answer this question: "I can create nearly 15 copies a week while stretching the quality, and for fantastic copies, my numbers linger around 7 to 9." This type of answer will compliment your honesty, which is one remarkable attitude HR is looking for.