Statistics - Bayes Theorem

Question

Am I right in thinking this is a Bayes Theorem question, if so how would I rearrage/model the formulae for the question?

Many thanks.

Answer 1

I find it easier to do this sort of problem with a table. Make up an imaginary sample of 10,000 women that will follow the rules of the problem. (You can use any "nice" number. Because of the percents, use a power of 10.)

First, find the totals at the far right. Then apply the test to those subgroups.

Test Result Totals

+ -

has b cancer 90%(100) = 90 1%(10,000) = 100

does not have b cancer 8%(9900) = 792 99%(10,000) = 9900

Totals

Then see if you can fill in the test -(minus) column and the totals of all 3 columns.

Once the table is complete, you should be able to answer probability questions, all without formulas!

Your particular question can be answered just by using the first column of numbers.