5. A tombola contains 5 red balls and 5 black balls. If 3 balls are chosen at random, what is the probability that all three balls are red? 6. Suppose the prevalence of COVID is 12.5%. We assume that the diagnostic test has a sensitivity of 80% and a specificity of 95%. What is the probability of getting a negative result? 7. Assume the prevalence of breast cancer is 13%. The diagnostic test has a sensitivity of 86.9% and a specificity of 88.9%. If a patient tests positive, what is the probability that the patient has breast cancer?