I would like to check my knowledge of foreign words by sampling a N words dictionnary: after checking randomly n words I would find that I know k of them (and do not know n-k).
How should I choose n so that the sampling is representative (= so that I could say I know N k/n words)?
There is not good answer for that question because everything depend on how many words you really know. Lets assume that you know all words from the dictionary then any n gives you right answer as n=k, but if you know only one word then you will have to check entire dictionary to be sure that you have right results. As you do not know how many words you know as you want to discover it then checking entire dictionary is probably the only way