Calculate Mrs. Ncube's monthly water bill for September 2025, given her weekly usage and the water tariff structure, including VAT.

Step 1: Calculate Mrs Ncube's water usage for the month of September 2025 (2.1.1).
Given that her water usage for 1 week is 3 125 litres, and assuming a month has 4 weeks:

$$\text{Monthly water usage} = \text{Water usage per week} \times 4$$ $$\text{Monthly water usage} = 3\,125 \text{ litres/week} \times 4 \text{ weeks}$$ $$\text{Monthly water usage} = 12\,500 \text{ litres}$$ $$\boxed{12\,500 \text{ litres}}$$

Step 2: Convert monthly water usage to kilolitres (2.1.2).
To convert litres to kilolitres, we divide by 1 000 (since 1 kL = 1 000 L).

$$\text{Water usage in kilolitres} = \frac{12\,500 \text{ litres}}{1\,000 \text{ L/kL}}$$ $$\text{Water usage in kilolitres} = 12.5 \text{ kL}$$ $$\boxed{12.5 \text{ kL}}$$

Step 3: Calculate the cost of 15 kL of water, excluding VAT (2.2.1).
We use the provided water tariff table for 15 kL:

• Block 1: 0 kL - 6 kL is free. Cost for first 6 kL = R0.00.
• Block 2: >6 kL - 10 kL costs R7.20 per kL. This block covers $10 - 6 = 4$ kL. Cost for 4 kL = $4 \text{ kL} \times \text{R}7.20/\text{kL} = \text{R}28.80$.
• Block 3: >10 kL - 15 kL costs R13.08 per kL. This block covers $15 - 10 = 5$ kL. Cost for 5 kL = $5 \text{ kL} \times \text{R}13.08/\text{kL} = \text{R}65.40$.

Total cost for 15 kL (excluding VAT) = Cost from Block 1 + Cost from Block 2 + Cost from Block 3

$$\text{Total cost (excluding VAT)} = \text{R}0.00 + \text{R}28.80 + \text{R}65.40$$ $$$$