SOLUTION: The chance that a student passes an exam is 60%.Each time the student fails and repeats the exam the chance of passing increases by 15%. Determine the probability that the student

Question 1201917: The chance that a student passes an exam is 60%.Each time the student fails and repeats the exam the chance of passing increases by 15%. Determine the probability that the student passes the exam during the second or the third attempt.

Answer by greenestamps(13216) (Show Source): You can put this solution on YOUR website!

Obviously the correct information is that the probability that the student passes the exam is 60% ON THE FIRST TRY....

Then, from the given information....

P(pass on first try) = 0.60
P(pass on second try) = 0.75
P(pass on third try) = 0.90

To pass on the second try, the student must fail on the first try AND pass on the second: P = (.40)(.75) = .30

To pass on the third try, the student must fail on the first try AND fail on the second try AND pass on the third try: P = (.40)(.25)(.90)=.09

To pass on the second OR third try, the probability is (.30)+(.09) = .39

ANSWER: 0.39, or 39%

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