The cost of electricity for using a kettle is K80.00 at a cost of K0.65 per unit (kWh). It takes 5minutes to boil water in a day and the kettle is used for 30 days. What is the power rating of the kettle?

The total cost of electricity for using the kettle is K80.00, and the cost per unit is K0.65 per kWh.

$$\text{Total Energy (kWh)} = \frac{\text{Total Cost}}{\text{Cost per unit}}$$ $$\text{Total Energy (kWh)} = \frac{\text{K}80.00}{\text{K}0.65/\text{kWh}}$$ $$\text{Total Energy (kWh)} \approx 123.0769 \text{ kWh}$$

The kettle takes 5 minutes to boil water, and it is used for 30 days. Assuming it is used once per day:

$$\text{Total Operating Time (minutes)} = 5 \text{ minutes/day} \times 30 \text{ days}$$ $$\text{Total Operating Time (minutes)} = 150 \text{ minutes}$$

Convert the total operating time from minutes to hours:

$$\text{Total Operating Time (hours)} = \frac{150 \text{ minutes}}{60 \text{ minutes/hour}}$$ $$\text{Total Operating Time (hours)} = 2.5 \text{ hours}$$

The power rating (in kW) is the total energy consumed divided by the total operating time.

$$\text{Power (kW)} = \frac{\text{Total Energy (kWh)}}{\text{Total Operating Time (hours)}}$$ $$\text{Power (kW)} = \frac{123.0769 \text{ kWh}}{2.5 \text{ hours}}$$ $$\text{Power (kW)} \approx 49.23076 \text{ kW}$$

Rounding to two decimal places, the power rating is $49.23 \text{ kW}$.

This matches option C.

The final answer is $\text{C. } 49.23\text{kW}$