The 2500W heater is used in a country where electricity costs 0.30 dollars per kilowatt-hour. Calculate the cost of using the heater continuously for two days.

Sure, here are the steps to calculate the cost:

1. First, convert the power of the heater from watts to kilowatts. 1 kilowatt is equal to 1000 watts. So, 2500W = 2.5kW.

2. Next, calculate the total hours the heater is used. There are 24 hours in a day, so for two days, the heater is used for 24*2 = 48 hours.

3. Now, calculate the total energy consumed by the heater. The energy consumed (in kilowatt-hours) is the power of the heater (in kilowatts) multiplied by the time it's used (in hours). So, the energy consumed is 2.5kW * 48 hours = 120 kWh.

4. Finally, calculate the cost of using the heater. The cost is the energy consumed (in kilowatt-hours) multiplied by the cost per kilowatt-hour. So, the cost is 120 kWh * $0.30/kWh =$36.

So, the cost of using the heater continuously for two days is $36.