SOLUTION: Statistic question
A psychology professor gives a surprise quiz consisting of 10 true/false questions, and she states that passing requires at least 7 correct responses. Assume
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A psychology professor gives a surprise quiz consisting of 10 true/false questions, and she states that passing requires at least 7 correct responses. Assume
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Question 764227: Statistic question
A psychology professor gives a surprise quiz consisting of 10 true/false questions, and she states that passing requires at least 7 correct responses. Assume that an unpreprated student adopts the questionable strategy of guessing for each anser.
a. find the probability that the first 7 responses are correct and the last 3 are wrong.
b. is the probability from part a equal to the probability of passing? why or why not?
Please help!!!
Thank you. Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website! If one is guessing, then the probability of getting a correct answer is 1/2 and the probability of getting an answer wrong is also 1/2.
Probability that the first 7 answers are correct is (1/2)^7 = .008
Probability that the last three answers are false is (1/2)^3 = .125
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a) sum the two probabilities, .008 + .125 = .133
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b) answer is no - because there are multiple ways to get 7 answers correct when guessing:
there are 7 ways to get a passing grade by guessing
7 0 0 3
6 1 1 2
5 2 2 1
4 3 3 0
3 1 4 2
2 2 5 1
1 3 6 0
multiply 7 times .008 = .056
