Random samples of two species of iris gave the following petal lengths (in cm). x1, Iris virginica 5.8 5.9 4.5 4.9 5.7 4.8 5.8 6.4 5.3 5.9
x2, Iris versicolor 4.5 4.9 4.7 5.0 3.8 5.1 4.4 4.2

Required:
a. Use a 5% level of significance to test the claim that the population standard deviation of x1 is larger than 0.55.
b. What are the degrees of freedom?
c. Find a 90% confidence interval for the population standard deviation of x1.
d. Find the value of the sample F statistic.