Example: Hemoglobin determinations were made on 16 animals exposed to a harmful chemical. The following observations were recorded: 15.6, 14.8, 14.4, 16.6, 13.8, 14.0, 17.3, 17.4, 18.6, 16.2, 14.7, 15.7, 16.4, 13.9, 14.8, 17.5. Find the 95 percent confidence intervals for σ².

11. The following measurements were recorded for the drying time , in hours, of a certain brand of latex paint: 3.4 2.5 4.8 2.9 3.6 2.8 3.3 5.6 3.7 2.8 4.4 4.0 5.2 3.0 4.8 Assuming that the measurements represent a random sample from a normal population, find a 96% confidence interval for the drying time.

In a sample of seven cars, each car was tested for nitrogen oxide emissions (in grams per mile). The results appear below. Assuming that nitrogen oxide emissions are normally distributed, 4. Car 1 2 3 4 5 6 7 Nitrogen oxide emission (g/mi) 0.13 0.18 0.15 0.09 0.12 0.18 0.08 a. Construct a 95% confidence interval for the mean amount of nitrogen oxide emissions for all cars. b. What effect would increasing the level of confidence have on the length of the interval?

At a charter high school, the average GPA of a high school senior is known to be normally distributed. After a sample of 27 seniors is taken, the average GPA is found to be 2.85 and the sample variance is determined to be 0.16. Find a 95% confidence interval for the population mean GPA.   a. 2.5615 to 2.8585 b. 2.6358 to 3.0642 c. 2.6917 to 3.0083 d. 2.5167 to 2.9033