Hello! I have a stat exam tomorrow, and for the life of me cannot figure out this practice problem about the F distribution. My teacher supplied the...

Hello! I have a stat exam tomorrow, and for the life of me cannot figure out this practice problem about the F distribution. My teacher supplied the answers but I cannot figure out how she got there. Can you also explain how to get the df from the table? My teachers answer says it is 3.82, but I can't understand why it wouldn't be 1.58. Thank you!

Random samples of n1=15 and n2=10 are selected from populations 1 and 2 respectively. the corresponding sample standard deviations are s1=5.3 and s2=8.8.

a) Do the data provide sufficient evidence (a=.05) to indicate a difference in SD1 and SD2? Use rejection region approach.

b) Place a 95% confidence interval on the ratio of the variances (sd1 squared / sd2 squared).

c) what assumptions have you made concerning the data and populations when making your calculations in parts a and b?

Thank you so much for your time!