1. **Problem statement:** We have a rectangular oil tank with dimensions 5 m (length), 3 m (height), and 2 m (width). The oil fills the tank to a depth of 1.2 m. We need to find the volume of oil in the tank and convert it to litres. 2. **Formula for volume of a rectangular prism:** $$\text{Volume} = \text{length} \times \text{width} \times \text{height}$$ 3. **Apply the formula to the oil volume:** Since the oil depth is 1.2 m (less than the tank height), the volume of oil is: $$\text{Volume of oil} = 5 \times 2 \times 1.2$$ 4. **Calculate the volume:** $$5 \times 2 = 10$$ $$10 \times 1.2 = 12$$ So, the volume of oil is 12 cubic metres. 5. **Convert cubic metres to litres:** Given 1 cubic metre = 1000 litres, $$12 \text{ cubic metres} = 12 \times 1000 = 12000 \text{ litres}$$ **Final answer:** The quantity of oil in the tank is **12000 litres**.