GROWTH DEVELOPMENT CHILD
SUMMATIVE ASSESSMENT
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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You compute a 95% confidence interval with sample size 50, a sample mean of 20, and a sample standard deviation of 7. You then compute a 90% confidence interval with the same sample data. For these two confidence intervals, which of the statements is true?
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The 90% confidence interval is narrower.
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The 95% confidence interval is narrower.
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The intervals have the same width.
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There is no way to know which interval is wider.
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Explanation:
Detailed explanation-1: -Since 95% of values fall within two standard deviations of the mean according to the 68-95-99.7 Rule, simply add and subtract two standard deviations from the mean in order to obtain the 95% confidence interval.
Detailed explanation-2: -A 95% confidence interval is a range of values above and below the point estimate within which the true value in the population is likely to lie with 95% confidence. The other 5% is the possibility that the true value is not within the confidence interval.
Detailed explanation-3: -The standard error is most useful as a means of calculating a confidence interval. For a large sample, a 95% confidence interval is obtained as the values 1.96×SE either side of the mean.
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