Section 8.4 Summary

1. The continuous random variable takes values that are never negative, so the distribution curve starts at 0 and extends indefinitely to the right. Thus, the curve is right-skewed and not symmetric. There is a different curve for every different degrees of freedom, . To find critical values, we can use either the table or technology.

2. If the population is normally distributed, we use the distribution to construct a confidence interval for the population variance , which is given by

   where represents the sample variance and and are the critical values for a distribution with degrees of freedom. The confidence interval for is found by taking the square root of these lower and upper bounds.