The following data represent petal lengths (in cm) for independent random samples of two species of iris. Petal length (in cm) of Iris virginica: x ; n, = 36 5.2 5.6 6.1 6, 1 5,1 5, 5.3 5.5 6.9 5.0 1.9 6.0 4.8 5.6 5.1 5.6 48 5.4 5,1 5.1 5.9 5.2 5.7 5.4 4.5 5.4 5.3 5.5 6.7 5.7 4,9 4.8 5.8 5.3 5.3 Petal length (in cm) of Iris setosa: x,; n, = 38 1.4 1.8 1.4 1,5 1.5 1,6 1.4 1,2 1.4 1.7 1.0 1,7 1,9 1,6 1.4 15 1.4 1.2 1.3 1.5 1.3 1.6 1.9 1.4 1.6 1.5 1.4 1.6 1.2 1.9 1.5 1.6 1.4 1,3 1.7 1.5 1.5 LA USE SALT (a) Use a calculator with mean and standard deviation keys to calculate X,, S,, X2, and $2. (Round your answers to four decimal places.) X 2 two decimal places.) (b) Let #, be the population mean for x, and let /, be the population mean for x2 . Find a 99% confidence interval for u, - #2. (Round your answers to lower limit upper limit