A blood test to detect the presence of a certain disease successfully detects the disease in out of every patients who actually have the disease. But it falsely indicates the presence of the disease in out of every healthy persons. percent of the population has the disease. The test is administered to a randomly selected person. What is the probability that she has the disease given that her test result is positive?
Tap an option to check your answer.
Checking your account…
A blood test to detect the presence of a certain disease successfully detects the disease in 99 out of every 100 patients who actually have the disease. But it falsely indicates the presence of the disease in 1 out of every 100 healthy persons. 1 percent of the population has the disease. The test is administered to a randomly selected person. What is the probability that she has the disease given that her test result is positive? (A) 2/3 (B) 1/2 (C) 3/4 (D) 3/5
Probability and Bayes' theorem has come up 190 times in 7 exams since 2004.
This question is on Total probability and Bayes' theorem, part of Probability and Bayes' theorem in Statistics.
Reversing a conditional probability and updating beliefs from evidence.
TestStop has 22 past-paper questions on this subtopic.
Question from the DSE 2005 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.