Question 884763: A field test for a new exam was given to randomly selected freshmen. 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 6% of 80%.
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 freshmen. The exams were graded, and the sample mean and sample standard deviation were calculated.
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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 6% of 80%.
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Is the confidence interval at 90%, 95%, or 99%?
Ans:: 9 out of 10 = 90%
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What is the margin of error?
Ans: 2*ME = 80%-6% = 72%
ME = 36%
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Calculate the confidence interval and explain what it means in terms of the situation.
90% CI:: 0.06 < p < 0.80
We have 90% confidence the population proportion is between 6% and 80%
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Cheers,
Stan H.
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