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A particular professor is known for his arbitrary grading
Chapter , Problem 40(choose chapter or problem)
A particular professor is known for his arbitrary grading policies. Each paper receives a grade from the set {A, A-, B+. B, B-, C+}, with equal probability, independent of other papers. How many papers do you expect to hand in before you receive each possible grade at least once?
Questions & Answers
QUESTION:
A particular professor is known for his arbitrary grading policies. Each paper receives a grade from the set {A, A-, B+. B, B-, C+}, with equal probability, independent of other papers. How many papers do you expect to hand in before you receive each possible grade at least once?
ANSWER:Step 1 of 3
Let denotes random variable which signifies that number of trial needs to get new grade.
So at i = 1, we need 1 trail to get first new grade.
So,