7. To compare the durability of brand A or B tires for its fleet of taxis, a taxi company collects two random samples from a fleet of 32 taxis, by randomly choosing 16 vehicles to run on brand A tires and the remaining 16 vehicles to run on brand B tires. The tires are run until they wear out. The following table shows the sample average and sample standard deviations of wear (all in thousands of kilometers) for each brand. Brand A TA = 37.0 SA = 3.0 Brand B CB = 39.6 SB = 4.0 Assume that the durabilities (wear in thousands of km.) for each brand are normal populations with equal variances o'. Find both a 90% and a 97% confidence interval for the difference in population means #B - PA. What conclusions do you draw? Show all formulae that you apply