20.

Human blood is classified by the presence or absence of three main antigens (A, B, and Rh). When a blood specimen is typed, the presence of the A and/or B antigen is indicated by listing the letter A and/or the letter B. If neither the A nor the B antigen is present, the letter O is used. The following table gives the percent of a certain country's population having each of the eight possible blood types in the sample space. Note that the presence or absence of the Rh antigen is indicated by the symbols + or -, respectively. Blood Types At A- B+ B- AB+ AB O+ O- Percent 35.7 6.1 8.5 2.5 3.4 0.6 37.4 5.8 (a) What is the probability that a person selected randomly from the population has a blood type that is type O or Rh+? (b) What is the probability that a person selected randomly from the population has a blood type that contains the A antigen? (c) What is the probability that a person selected randomly from the population has a blood type that is type AB or Rh