Question 986290: A field test for a new exam was given to randomly selected seniors. The exams were graded, and the sample mean and sample standard deviation were calculated. Based on the results, the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 4% of 70%.
Is the confidence interval at 90%, 95%, or 99%? What is the margin of error? Calculate the confidence interval and explain what it means in terms of the situation.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A field test for a new exam was given to randomly selected seniors. The exams were graded, and the sample mean and sample standard deviation were calculated. Based on the results, the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 4% of 70%.
Is the confidence interval at 90%, 95%, or 99%?
Ans: 9 out of 10 is 90%
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90% CI:: 0.66 < p < 0.74
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What is the margin of error?
Note The range of the CI is 2*ME
2ME = 0.74-0.66 = 0.08
ME = 0.04 or 4%
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Calculate the confidence interval and explain what it means in terms of the situation.
We are 90% confident that that a random senior's score will
be between 66% and 74%
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Cheers,
Stan H.
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