You've tested positive for cancer! How worried should you be?
This is a reasonably simple mathematical problem, with a very startling result.
The premise is this:
We have a test for cancer that is 98% accurate. That is, that 98% of the subjects who do have cancer will test positive, and 98% of the subjects who do not have cancer will test negative.
You've undergone the test, and the results have come back.
Bad news! You've tested positive!
But the question is, how worried should you be?
Given that 0.5% of the population has cancer, what is the probability that you have cancer, having recieved a positive result?
(Hint: If you don't know where to begin, apply the values to a set population of say 10,000 and work from that)
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