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Suppose you know that the IQ scores of all incoming college freshman are normally distributed with...

Suppose you know that the IQ scores of all incoming college freshman are normally distributed with standard deviation of 15. You have a simple random sample of 100 freshmen, and the mean IQ score for this sample is 120. Find a 90-percent confidence interval for the mean IQ score for the entire population of incoming college freshmen

Math   Statistics-And-Probability   
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Here we know population standard deviation hence we use z test.If population standard deviation is unknown then we use t test .

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