Content
Access custom-built, exam-style problems for probability. Each problem has a full solution and mark-scheme, as well as AI grading and support.
Ask Plex AI about problem 33
Get hints, ask questions, and work through this problem step by step
Select a Difficulty:
14 / 46 problems visible - Upgrade to view all problems
!
0 / 14
A company producing COWID antigen tests finds that the probability that any one person has COWID at a given time is 2%. They find that the rate at which people without COWID test positive is 20% and that the rate at which people with COWID test positive is 90%.
Note: COWID is not a real virus. COVID antigen tests have a much lower false positive rate.
Determine the probability that a randomly selected person does not have COWID and tests negative.
Determine the probability that two randomly selected people do not have COWID and test negative.
Given that Ray has a positive test result, find the probability that he has COWID.
Of a sample of 1000 quarantined people (i.e. people with positive test results), find the expected number without COWID.
The government does not like the current antigen test from the company because of its very high false positive rate. They take a random sample of 20 people who tested positive. If 2 or fewer have COWID, they will stop funding research at this company.
Find the probability that this company will be defunded.
!
0 / 15
!
0 / 14
!
0 / 6
!
0 / 13
!
0 / 14
!
0 / 9
!
0 / 13
!
0 / 8