Question

The data represent the results for a test for a certain disease. Assume one individual from the group is randomly selected. Find the probability of getting someone who tests negative, given that he or she did not have the disease. Round to three decimal places as needed.

Yes - Have the disease No - Do not have the disease
Positive 142 6
Negative 7 145

Answer 1

0.505 = 50.7% probability of a negative test.

Explanation:

A probability is the number of desired outcomes divided by the number of total outcomes.

In this question:

142 + 6 = 148 people tested positive. Of those, 142 had the disease and 6 did not.

7 + 145 = 152 people tested negative. Of those, 7 had the disease and 145 did not.

Find the probability of getting someone who tests negative, given that he or she did not have the disease.

This is the probability of a negative test.

152 negative tests out of 148 + 152 = 300

152/300 = 0.507

0.505 = 50.7% probability of a negative test.