STATISTICAL TECHNIQUES AND TOOLS
T DISTRIBUTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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For a sample of size 20 taken from a normally distributed population with standard deviation equal to 5, a 90% confidence interval for the population mean would require the use of ____
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Explanation:
Detailed explanation-1: -If the population standard deviation is unknown and the sample size n is small then when we substitute the sample standard deviation s for the normal approximation is no longer valid. The solution is to use a different distribution, called Student’s t-distribution with n−1 degrees of freedom.
Detailed explanation-2: -IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. About 68% of individuals have IQ scores in the interval 100 ± 1 ( 15 ) = [ 85, 115 ] .
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