(a) for a nonsmoker, with blood viscosity of 2.50 10-3 pa·s, normal blood flow requires a pressure difference of 8 mm hg between the two ends of a certain artery. if this person were to smoke regularly, his blood viscosity could increase to 2.83 10-3 pa·s (a 13% increase), and the diameter of his artery would constrict by 11%. what pressure difference between the ends of the artery would then be needed to maintain the same blood flow rate?