An electric refrigerator has a power rating of 500 W and is used for 6 hours each day. If the cost of electrical energy is ₹4.00 per kilowatt-hour, what will be the total cost of operating the refrigerator for 30 days?

The correct option is ₹360.

Given Data:
Power rating of the refrigerator ($P$) = 500 W
Usage duration per day ($t$) = 6 hours
Total duration ($N$) = 30 days
Cost of electrical energy = ₹4.00 per kilowatt-hour (kWh)

Step 1: Calculate the total energy consumed by the refrigerator.
Electrical energy consumed is calculated as the product of power and time. First, let us convert the power rating from watts (W) to kilowatts (kW) since energy cost is given per kilowatt-hour (kWh):

$\text{Power}\left(P\right)=\frac{500}{1000}\text{kW}=0.5\text{kW}$

Next, we determine the total operating hours over the 30-day period:

$\text{Total time}\left(T\right)=6\text{hours/day}\times 30\text{days}=180\text{hours}$

Now, we calculate the total electrical energy consumed ($E$) in kilowatt-hours (kWh):

$\text{Total Energy}\left(E\right)=\text{Power}\left(P\right)\times \text{Total time}\left(T\right)$

$E=0.5\text{kW}\times 180\text{hours}=90\text{kWh}$

Step 2: Calculate the total cost of operation.
With the rate of electrical energy being ₹4.00 per kWh, we multiply the total energy consumed by the rate to find the final cost:

$\text{Total Cost}=\text{Total Energy}\left(E\right)\times \text{Rate per kWh}$

$\text{Total Cost}=90\text{kWh}\times ₹4.00/\text{kWh}=₹360$

Therefore, the total cost of operating the refrigerator for 30 days is ₹360.