Calculation practice: General addition rule. Among women voluntarily tested for sexually transmitted diseases in one university, 24% tested positive for human papilloma virus (HPV) only, 2% tested positive for Chlamydia only, and 4% tested positive for both HPV and Chlamydia (Tábora et al. 2005). Use the following steps to calculate the probability that a woman from this population who gets tested would test positive for either HPV or Chlamydia.

a. Write the goal of the question as a probability statement.

b. Write the general addition rule with words specific to this example.

c. Calculate the probability that a randomly sampled woman would test positive for HPV or Chlamydia.