Question

A medical condition affects about 20% of non-Hispanic White Americans, 50% of Hispanic Americans, and 80% of African, Asian, and Native Americans. Seventy-six percent of U.S. residents are non-Hispanic Whites, 9% of them are Hispanic, and 15% are African, Asian, or Native American. If a person is selected from this group of people, what is the probability that the person will have the medical condition? (Give an exact answer. Do not round.)

I had 0.3095 and it was wrong.

Answer 1

P(non-Hispanic White Americans) = 0.76

P(Hispanic) = 0.09

P(frican, Asian, or Native American) = 0.15

P(medical condition | non-Hispanic White Americans) = 0.2

P(medical condition | Hispanic) = 0.5

P(medical condition | African, Asian, or Native American) = 0.8

P(medical condition) = P(medical condition | non-Hispanic White Americans) * P(non-Hispanic White Americans) + P(medical condition | Hispanic) * P(Hispanic) + P(medical condition | African, Asian, or Native American) * P(African, Asian, or Native American)

                       = 0.76 * 0.2 + 0.09 * 0.5 + 0.15 * 0.8

                       = 0.317