Calculate the cost of 2569 kWh of electricity and suggest two ways Mrs Smith can reduce her electricity cost.

The electricity is charged on a sliding scale:

• $0 - 500 \text{ kWh}$: $500 \text{ kWh} \times 105.75 \text{ c/kWh} = 52875 \text{ cents}$
• $>500 - 1000 \text{ kWh}$: $500 \text{ kWh} \times 129.82 \text{ c/kWh} = 64910 \text{ cents}$
• $>1000 - 2000 \text{ kWh}$: $1000 \text{ kWh} \times 130.75 \text{ c/kWh} = 130750 \text{ cents}$
• $>2000 - 3000 \text{ kWh}$: $(2569 - 2000) \text{ kWh} \times 132.09 \text{ c/kWh} = 569 \text{ kWh} \times 132.09 \text{ c/kWh} = 75160.21 \text{ cents}$

Total cost excluding VAT:

Convert to Rands:

Assuming a standard VAT rate of $15\%$:
VAT amount:

Total cost including VAT:

Rounding to two decimal places:

The cost of her purchase including VAT is $\boxed{\text{R}3722.49}$.

• Use energy-efficient appliances (e.g., LED lighting, A-rated appliances).
• Switch off lights and appliances when not in use.

The original tariff is $132.09 \text{ c/kWh}$.

New tariff = Original tariff $\times (1 + \text{percentage increase})$

Rounding to two decimal places:

The new tariff per unit for units between 2001 and 3000 kWh is $\boxed{152.56 \text{ c/kWh}}$.

• $0 - 500 \text{ kWh}$: $500 \text{ kWh} \times 105.75 \text{ c/kWh} = 52875 \text{ cents}$
• $>500 - 1000 \text{ kWh}$: $500 \text{ kWh} \times 129.82 \text{ c/kWh} = 64910 \text{ cents}$
• $>1000 - 2000 \text{ kWh}$: $(1031.03 - 1000) \text{ kWh} \times 130.75 \text{ c/kWh} = 31.03 \text{ kWh} \times 130.75 \text{ c/kWh} = 4059.4325 \text{ cents}$

Total cost excluding VAT:

Convert to Rands:

Assuming a standard VAT rate of $15\%$:
VAT amount:

Total cost including VAT:

Rounding to two decimal places:

Mrs Smith claimed she paid R1389. Our calculation shows the cost is R1401.21.
Since $\text{R}1401.21 \neq \text{R}1389$, her claim is not valid.