12. READING During the summer, Bernardo read three times as many books as Kyle. Elan read twice as many books as
Kyle. Nate read the same number of books as Bernardo,
Kyle, and Elan combined, If Nate read 36 books, how many
books did each of the other boys read?

Researchers are conducting experiments to determine the role of alcohol in the development of depression. after the study is complete, they determine that the relative risk of developing depression is 1.55 with a 95 % ci of 1.2 -1.9. each group is then divided into nonsmokers and smokers. the relative risk for the nonsmokers is 1.12 with a 95% ci of 0.87-1.37. the relative risk for the smokers is 1.7 with a 95 % cl of 1.5-1.9. what type of bias may affect this study? a. procedure bias b. recall bias c. selection bias d. confounding e. lead-time bias