SOLUTION: An instructor gives a pop quiz consisting of 10 multiple choice questions, where each question has 5 choices, (a) through (e). What is the probability of passing the pop quiz if yo

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Question 1055830: An instructor gives a pop quiz consisting of 10 multiple choice questions, where each question has 5 choices, (a) through (e). What is the probability of passing the pop quiz if you guess the answers? Passing means getting 8 out of 10 questions correct.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
There are 3 ways to pass
Guess all 10, a probability of 0.2^10=1 x 10^(-7)
Guess 9, which is 10 (10 different ways)(0.2^9)(0.8)=4 x 10^-6
Guess 8, of which there are 45 different ways, 0.2^8(0.8)^2=0.00007
Their sum is 0.0000741