Two different formulations of an oxygenated motor fuel are being tested to study their road octanenumbers. The variance of road
octane number for formulation 1 is ı2 = 1.5, and for formulation, 2it is ı2 = 1.2. Two random samples of size n1 = 15 and n2 = 20 are tested, and the mean roadoctane numbers observed are x1 = 89.6 and x2 = 92 5. Assume normality. Find the 95%confidence interval for the difference in the mean octane number.
