perplexus.info :: Probability : Are you ill?

Are you ill? (Posted on 2005-01-03)

Suppose an illness that can affect 1% of the people. Also assume that there is a test for that illness, that gives the correct result 99% of the times.

If you take that test, and receive a POSITIVE result, should you worry much?

If you take it again, and once more get a POSITIVE, should you worry then?

How many consecutive POSITIVEs would you have to get in order to be sure that the chances of a wrong diagnostic are 1 in a million?

See The Solution Submitted by e.g.

Rating: 3.7500 (4 votes)

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Puzzle Thoughts	K Sengupta	2023-04-30 22:52:11
re: Correct Solution (for real)	Marc	2005-10-19 23:10:44
Correct Solution.	A	2005-03-06 06:30:10
Implications to our justice system	ajosin	2005-02-28 14:46:13
re: Combined probabilities	Kyle	2005-01-07 15:37:44
re: Combined probabilities	DJ	2005-01-07 12:51:58
Combined probabilities	François	2005-01-06 17:16:22
perplexus in the news	Penny	2005-01-04 02:34:16
re(5): solution	Larry	2005-01-03 22:39:13
re(4): solution	Penny	2005-01-03 21:23:49
re(3): solution	Kyle	2005-01-03 21:15:43
re(2): solution	Larry	2005-01-03 20:37:44
re: This is a lousy example, but...	Eric	2005-01-03 20:25:07
This is a lousy example, but...	Penny	2005-01-03 20:08:16
re(2): solution	Eric	2005-01-03 20:05:06
re: solution	Penny	2005-01-03 18:26:15
solution	Charlie	2005-01-03 18:01:27
Is your terminology correct ?	Penny	2005-01-03 17:40:33
Meaning?	Angela	2005-01-03 17:28:48

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