(Total 100 Points.) There are 7 problems in this exam. Show intermediate steps and formu- las for partial credit. You must enplain how you compute your results or answers for full credit.
 1. (20 points) There an pussengers in this Hight are from cou e are 300 pa pasengers in an intornational fight. We know that 150, 100, and 50 untries A, B, and C, respectively. Fach pasenger may carry COVID-19 virus with a certain probablity independently. These probablities for the pasaangers from countries A, B, and C are 3%, 4%, and 5%, respectively.