A sample of four tires is taken from a lot of brand-A tires. Another sample of four tires is taken from a lot of Brand-B tires. These tires are tested for amount of wear, for 24,000 miles of driving on an eight-wheeled truck, when the tires are rotated every 1000 miles. The tires are weighted before and after the test. The loss in weight, expressed as the percentage of initial weight, is used as a measure of wear. For the sample of brand-A tires:
it is found that X-bar_A=18.0, S_A=1.3 ;
for brand-B tires, X-bar_B=19.4, S_B=1.5.
Assuming (approximately) normal distributions having equal variances for percent wear of tires of each brand under these test conditions, find a 95% confidence interval for \(\mu_{A}-\mu_{B}\)