Let n be an integer with n 2. Prove that n is prime if and only if all nonzero elements of Zn are invertible.

CHAPTER 8: CONFIDENCE INTERVALS FOR ONE POPULATION MEAN 8.1: Estimating a population mean • Common problem in statistics is to obtain information about the mean, ������������, of a population. • If population is small, we can ordinarily determine ������������ exactly by first taking a census and then computing ������������ from the population data. • If population is large, often in practice, taking census is generally impractical, extremely expensive, or impossible. Nonetheless, we can usually obtain sufficiently accura te information about ������������ by taking a sample from the population. Recall • A parameter is a characteristic of the population • A statistic is a characteristic of the sample Ex: • The population mean and population standard deviation are parameters • The sample mean and sample standard deviation are statistics Estimator Point estimator Interval estimator Estimation by single value Single value + error->interval • Point estimator Point estimate of a parameter is the value of statistics used to estimate the parameter. Point estimate of a population mean µ is a sample mean X . Example 01: The following is the simple random sample of price of 8 new mobile homes, in thousands of dollars. Use the data to find a point estimate of the population mean price of all mobile hoµe. X = Interpretation: Confidence Interval estimate • Confidence Interval (CI): An interva