The percentage of the population in a city who suffer from a serious disease is 3%.

A person has just taken two medical examinations to see whether he suffers from the disease. Each of the two tests make the correct diagnosis (whether someone suffers from the disease or not) with a probability 98% and the results of the two tests are independent. Calculate the probability that he has the disease

(i) given that at least one of the two outcomes of the tests is positive;

(ii) given that both tests give a positive result.