Explanation: Given; The dimension of RCC slab = 4 m × 5 m The thickness of slab = 175 mm There is a 0.2 m projection of slab all around the room, So the overall dimension of slab = (4 + 0.4) × (5 + 0.4) = 4.4 m × 5.4 m The total quantity of concrete = 4.4 × 5.4 × 0.175 = 4.158 m3