Members of the Saxophone Section of a Marching Band Are

Short Answer

Members of the saxophone section of a marching band are asked to attend saxophone-only practices once a week. These practices are not mandatory, but they are the only opportunity for the entire section to play together in preparation for the marching season. The section leader has noted that 70% of the section regularly attends practices. Further, given that they attend regularly, there is a 40% chance of earning an A on their performance when later graded by the band director. If they do not attend regularly, there is only a 10% chance of earning an A on their performance. What is the probability that a randomly chosen musician receives an A on their performance?