1. From a sample of size 20 taken from an approximately normal popula- tion it was determined that s2 = 5.36. Find a 90% confidence interval for σ .
2. A random sample of 17 high school students was selected from the senior class. It was found that the standard deviation of their summer hourly wage rates was $4.35. Find a 90% confidence interval for the true variance of the hourly wage rate for all seniors who had summer jobs. What assumption is required in order to find the said interval?