STATISTICAL TECHNIQUES AND TOOLS
T DISTRIBUTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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You want to compute a 90% confidence interval for the mean of a population with unknown population standard deviation. The sample size is 30. The value of the t-score you would use for this interval is ____
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1.96
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1.645
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1..699
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0.90
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1.311
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Explanation:
Detailed explanation-1: -To capture the central 90%, we must go out 1.645 standard deviations on either side of the calculated sample mean. The value 1.645 is the z-score from a standard normal probability distribution that puts an area of 0.90 in the center, an area of 0.05 in the far left tail, and an area of 0.05 in the far right tail.
Detailed explanation-2: -Suppose we want to generate a 95% confidence interval estimate for an unknown population mean. This means that there is a 95% probability that the confidence interval will contain the true population mean. Thus, P( [sample mean]-margin of error < < [sample mean] + margin of error) = 0.95.
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