[math-fun] Self-reference and probabilities

Hello Math-Fun, I don’t know if the hereunder words write a good and fluid English sentence, but you’ll get the idea: « Randomly draw a letter in this sentence and obtain an E will happen once in seven. » There are indeed 10 E’s and 70 letters altogether. This kind of sentence is easy to build (said my friend Pascal S. from Switzerland), but what would the English word-numbers Y and Z be here: « The odds of picking at random the four letters F, O, U, R in this sentence and in that order are Y out of Z. » Best, É.