Final answer:
The cost of operating a laptop that consumes 40 watts for 10 hours at a rate of $0.20 per kWh is $0.08.
Step-by-step explanation:
To calculate the cost of operating a laptop for 10 hours, we first need to convert its power consumption to kilowatts and then multiply it by the duration it is used to find the total energy consumed. After that, we multiply the energy consumed by the cost per kilowatt-hour to find the total cost.
Step-by-Step Calculation
Convert laptop's power consumption from watts to kilowatts: 40 watts = 0.040 kilowatts.
Calculate the energy used in kilowatt-hours (kWh): 0.040 kW × 10 hours = 0.400 kWh.
Multiply the energy used by the cost per kWh to find the total cost: 0.400 kWh × $0.20/kWh = $0.08.
The total cost of operating the laptop for 10 hours is $0.08.