Question 316639: Dr.Barton has been teaching basic statistics for many years. He knows that 80 percent of the students will complete the assigned problems. He has also determined that among those who do complete the assignment, 90 percent will pass the course. Among thise students who do not complete their assiggments, 50 percent will pass. Mike Fishman took statistics last semester from Dr. Barton and received a passing grade. What is the probability he completed the assignments?
This is what I got. Is it right? P(a)=0.80 P(p|a)=0.90 so .8*.9= 0.72
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Dr.Barton has been teaching basic statistics for many years. He knows that 80 percent of the students will complete the assigned problems. He has also determined that among those who do complete the assignment, 90 percent will pass the course. Among thise students who do not complete their assiggments, 50 percent will pass. Mike Fishman took statistics last semester from Dr. Barton and received a passing grade. What is the probability he completed the assignments?
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Let C = complete problems
Let P = pass course
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P(C|P) = [P(C and P)]/P(P) = [0.9*0.8]/[P(P&C))+P(P&C')] = 0.72/[0.72+0.10]
= 0.72/0.82 = 0.8780
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Cheers,
Stan H.
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