STATISTICAL TECHNIQUES AND TOOLS
CONFIDENCE INTERVALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A random sample of 85 sixth-graders in a large city take a course designed to improve scores on a reading comprehension test. Based on this sample, a 90% confidence interval for the mean improvement in test scores for all sixth-graders in the city taking this course is found to be (12.6, 14.8). Which of the following are the sample mean and margin of error on which this interval is based?
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Sample Mean = 13.7; Margin of Error = 1.1
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Sample mean = 13.7; Margin of Error = 2.2
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Sample mean is unknown; Margin of Error = 2.2
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None of the above
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Explanation:
Detailed explanation-1: -How does sample size affect the width of the confidence interval for the population mean? Larger sample sizes result in narrow intervals.
Detailed explanation-2: -Which of the following sources of error is included in the margin of error? Since the standard error is included in the margin of error, this is true. Remember, the standard error describes how close the sample statistic will be, on average, to the population parameter.
There is 1 question to complete.