Random samples of sizes n1 = 25 and n2 = 20 were selected from populations A and B, respectively. From the samples, the standard deviations were computed to be s1 = 5.2 and s2 = 6.8.
a. Do the data provide substantial evidence to indicate the populations have different standard deviations? Use α = .05.
b. Estimate the relative sizes of the standard deviations by constructing a 95% confidence interval for the ratio of the standard deviations σ1/σ2.
c. The data and populations must satisfy what conditions in order for your test and confidence interval to be valid?