# PROBABILITY MATH

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An unprepared student makes random guesses for the ten true-false questions on a quiz. Find the probability that there is at least one correct answer.

And explain to me how they got the answer?

and is there another way besides the tree method?

• PROBABILITY MATH -

All we have to exclude is the case when he guessed all of them wrong
that prob would be (1/2)^10 = 1/1024

so the prob of getting at least one correct is 1 - 1/1024 = 1023/1024

• PROBABILITY MATH -

Take 10/2=5
possibility of 5 right or 5 wrong because there is only two possible outcomes
2/100 = .50 (True and False Outcomes)
There are a total of 10 questions
.50^10 questions = .0009765625 rounded = .0009777
use the complement formula 1-P=
1-.0009777 = .9990223 that there is at least once correct answer

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