In many parts of the northern United States, two color variants of the Eastern Gray Squirrel— gray and black—are found in the same habitats. A scientist studying squirrels in a large forest wonders if there is a difference in the sizes of the two-color variants. He collects random samples of 40 squirrels of each color from a large forest and weighs them. The 40 black squirrels have a mean weight of 20.3 ounces and a standard deviation of 2.1 ounces. The 40 gray squirrels have a mean weight of 19.2 ounces and a standard deviation of 1.9 ounces.
Let 1= the true mean weight of black squirrels and 2= the true mean weight of gray squirrels.
Construct and interpret a 99% confidence interval for the difference between the true means. Use df = 30.
