A newly prepared mud sample in a rotational viscometer equipped with a standard torsion spring gives a dial reading of 45 when operated at 600 rpm and dial reading of 26 when operated at 300rpm. a. Compute the plastic viscosity and yield point. b. After drilling 200 ft of a formation, the solid volume fraction increased to 1.5%. Compute the new plastic viscosity? What would be the plastic viscosity if the solid concentration increases to 4%? C.