I wonder if perhaps you're trying to use 'cent' as a synonym for the number '100', which you can't do in English.
The word 'cent' does derive from the Latin word 'centum' meaning '100', but we don't use it as a number per se in English. It forms a base root for many English words related to 100, such as century (100 years), percent (per 100), cent (one penny or one hundredth of a dollar), or as a prefix for many units of measurement meaning 'one hundredth of' (centigram, centiliter, centimeter).
Of course, several Romance languages do use 'cent' (or a derivative of it) for the actual number one hundred, just not English.
However, if your first sentence was as attempt to say the person was only 1% correct , then you'd have to use something like "You are one percent correct."
However, that's a rather odd and unnatural way to express that someone is almost entirely incorrect. I'd assume it was an attempt at humor or hyperbole, because nobody would actually say that in seriousness.
Note also Charlie's correction regarding the difference of 'percent' (out of 100) vs. 'per cent' (per each cent).