A consumer electronics company is comparing the brightness of two different types of picture tubes for use in its television sets. Tube type A has mean brightness of 100 and standard deviation of 16, while tube type B has unknown mean brightness, but the standard deviation is assumed to be identical to that for type A. A random sample of n = 25 tubes of each type is selected, and XB - XA is computed. If = B equals or exceeds A, the manufacturer would like to adopt type B for use. The observed difference is xB - xA = 3.5. What decision would you make, and why?