1. Define a normal distribution. Show the step that you use to compute the probability by using a normal distribution with specific mean and specific variance (you can choose suitable values for the mean and variance in your example).2. State the central limit theorem. Describe simple random sampling. How would the sample mean of a simple random sampling be distributed? Give a numerical example showing that you calculated the likely hood of a sample mean to exceed a given value when the population mean, variance and the sample size is known?3. Describe the difference between and point estimate and an interval estimate. Give a numerical example showing the steps of constructing a confidence interval for a population mean.