A cancer test is 90 percent positive when cancer is present. It gives a false positive in 10 percent of the tests when the cancer is not present. If 2 percent of the population has this cancer what is the probability that someone has cancer given that the test is positive?

I multiplied the 90 by 10 divided by 90 times 10 plus 2.

I multiplied the 90 by 10 divided by 90 times 10 plus 2.