So, this is the question I'm working on:

Suppose we observe a random sample of five measurements: 10, 13, 15, 15, 17, from a normal distribution with unknown mean µ1 and unknown variance σ12.   A second random sample from another normal population with unknown mean µ2 and unknown variance σ22 yields the measurements: 13, 7, 9, 15, 11.

b. Use the pivotal method (and a pivotal statistic with F distribution) to derive a 95% confidence interval for σ2/σ1.  Work it out for these data.  And test the null hypothesis that σ2 = σ1 at the 5% level of significance.    [6]   (recall that Fv1,v2,a = 1/Fv2,v1,1-a). 

So, I'm completely at a loss as to how I can use the pivotal method on the F distribution. Please help me.