21. Some studies have shown that 1 in 177 Americans have celiac disease. Nevertheless, in general, for ordinary physicians, it is hard to diagnose it and, as a result, only 20% of the patients that have it are actually diagnosed with the disease. The good news is that of those who do not have celiac disease, 98% test negative. Hoyt is tested positive for this disease. However, to make sure, he is tested for a second time, and the result is positive again. Considering the results of both tests, what is the probability that Hoyt has celiac disease?