Question

Company A is developing a new pregnancy test. Based on their experiments, the test gives the correct result about 73% of the time, meaning the test result is positive when the person is pregnant, it is negative when the person is not pregnant.

Suppose that 45% of women who take the test are pregnant.

If the test result is positive, what is the probability that the person is truly pregnant?

You can express your answer as a fraction, decimal, or a percentage. If you answer in decimal, include at least 3 digits after the decimal point. If you answer is a percentage, make sure to include a % sign in your answer.

Answer 1

From the given data, the following Table is calculated:

	Pregnant	Not pregnant	Total
Test is positive	0.45 X 0.73 = 0.3285	0.1485	0.477
Test is negative	0.1215	0.55 X 0.73 = 0.4015	0.523
Total	0.45	0.55	1.00

P(Pregnant/ Test is positive) = P(Pregnant AND Test is positive) P(Test is positive)

                                         =0.3285/0.477

                                        = 0.689

So,

Answer is:

0.689