The viscosity of a fluid is to be measured by a viscometer constructed of two 5 ft-long concentric cylinders. The inner diameter of the outer cylinder is 6 inches. The gap between the two cylinders is 0.035 inch. and the gap is filled with fluid. The outer cylinder rotates at 250 rpm, and the torque is measured to be 1.2 lbf-ft. Determine the viscosity of the fluid and express it in appropriate units.