M1. At the end of their nal exam, 550 students answered an additional question in which they rated their instructor's teaching effectiveness, with the following results. Student's Rating of Instructor Student's Final Very or Somewhat Very or Somewhat Grade Effective Ineffective A 190 85 B 75 120 C 20 17 D F 9 18 l 15 What proportion of the students who rated their instructor as very or somewhat effective received a B or better in the class? a) 0.345 b) 0.254 c) 0.482 d) 0.898 c) 0.644