A professor finds that she awards a final grad of A to 22% of her students, and of these students, 72% got an A on the midterm examination. Also 12% of students who did not get a final grade of A earned an A on the midterm exam. What is the probability that a student with an A on the midterm examination will obtain a final grade of A?
22% of all student got A on the final 72% of the 22% got an A on the midterm = 15.84% of the total student got an A on both the midterm and final 12% of the student who did not get an A on the final got an A on the midterm [12% x (1-22%)] = 9.36% 15.84%/(15.84%+9.36%) = 62.85% or 0.6285 希望可以帮助
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发表于 2008-9-9 06:35:00
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