Question

Suppose a quiz contains 20 true/false questions. You know the correct answer to the first 10 questions. You have no idea of the correct answer to questions 11 through 20 and decide to answer each using the coin toss method. Calculate the probability of obtaining a total quiz score of at least 85%.

Answer 1

So we know answer to first 10 question so we get 50% score automatically

out of remaining 10 question we need to answer 7 question correctly to get atleast 85% score

This is a binomial distribution question with
n = 10
p = 0.5
q = 1 - p = 0.5
where

x = 7

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