To estimate the numerator, I used the fact that every known case of CJD is fatal, and there have been about 140 cases of CJD associated to the British epidemic. From this I concluded there were about 140 disease-inducing-servings. Since it is known that it may take many years for symptoms to arise, this number may not accurately reflect the number of people who will die from a disease-inducing-serving. It is likely that this number is an underestimate. Another assumption we need is that a given individual was unlikely to have received two disease-inducing-servings. Given how rare the disease was in humans and the assumptions discussed earlier, this assumption seems reasonable.