Final answer:
The cost of operating a 4.00 W electric clock for a year with an electricity cost of $0.0870 per kWh is approximately $0.0300.
Step-by-step explanation:
The question asks about the cost of operating an electric clock. To calculate this, you need to use the formula Cost = Power (in kW) × Time (in hours) × Cost per kWh. Since we have a 4.00 W clock and electricity costs $0.0870 per kWh, let's convert the power to kW and calculate the total hours in a year, which is 4 W × 1 kW/1000 W = 0.004 kW and 365 days × 24 hours/day = 8760 hours, respectively.
Now, we can find the cost:
Cost = 0.004 kW × 8760 hours × $0.0870/kWh
The calculated cost comes out to $0.0305 annually. Considering the options provided, the closest cost (rounded to the nearest hundredth of a dollar) is $0.0300 (Option a).