It is required to make a plastering of sand and cement with 3.5 cm thick, surrounding four cylindrical pillars, each of whose diameter is 17.5cm. (i) If each pillar is of 3 meter height, let us write by calculating how many cubic dcm of plaster materials will be needed. (ii) If the ratio of sand and cement in the plaster material be 4:1, let us write how many cubic dcm of cement will be needed.