Researchers at a local public health office are interested in the difference in prevalence of sickle cell anemia by ethnicity in a population under its jurisdiction. Suppose the following table represents prevalence of sickle cell anemia reported based on a thorough survey. Ethnicity Prevalence of Sickle Cell African-American =242/1049 Other =165/1864 A) Calculate the risk difference between the groups. B) Conduct a formal test to determine if there is a significant difference in the prevalence of sickle cell anemia between the two groups. Write out your null and alternative hypotheses and interpret your results. Use an alpha level of 0.05