Section 2: Estimating with Small Samples

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Section 2: Estimating with Small Samples Chapter 8: Estimation Section 2: Estimating with Small Samples

Student’s T Distribution degrees of freedom df = n – 1 population of x values must be normal or approximately normal resembles the standard normal curve total area under curve = 1 centered at 0 symmetric about 0 more spread out than the standard normal curve as n gets large, df gets large, curve gets closer to the standard normal curve

Confidence Interval

Example A company has a new process for manufacturing large artificial sapphires. In a trial run, 12 sapphires are produced. The mean weight for these 12 gems is 6.75 carats, with a standard deviation of 0.33 carat. Find a 95% confidence interval for the population mean.