3. Testing and Estimating Variances: Iris Random samples of two species of iris gave the following petal lengths (in cm) (Reference: R. A. Fisher, Annals of Eugenics, Vol. 7).

x1, Iris virginica 5.1 5.9 4.5 4.9 5.7 4.8 5.8 6.4 5.6 5.9 x2, Iris versicolor 4.5 4.8 4.7 5.0 3.8 5.1 4.4 4.2

(a) Use a 5% level of significance to test the claim that the population standard deviation of x1 is larger than 0.55.

(b) Find a 90% confidence interval for the population standard deviation of x1.

(c) Use a 1% level of significance to test the claim that the population variance of x1 is larger than that of x2. Interpret the results.