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A 10 W light bulb is turned on and left on continuously. How long can the bulb stay on with $2.00 if the energy cost is $0.05 per kW-hr?

A. 100 hours
B. 15 seconds
C. 4000 hours
D. 15 minutes
E. 1.7 hours

1 Answer

1 vote

Final answer:

A 10W light bulb can stay on for 4000 hours on a $2.00 budget with an energy cost of $0.05 per kWh.

Step-by-step explanation:

The question asks us to determine how long a 10W light bulb can stay on with $2.00 given the energy cost is $0.05 per kWh. First, we convert the power of the light bulb into kilowatts: 10 W is equal to 0.01 kW. Then, we calculate how many kilowatt-hours (kWh) we can purchase with $2.00 at a rate of $0.05 per kWh: $2.00 / $0.05/kWh = 40 kWh. Next, we determine how many hours the bulb can stay on by dividing the total kWh purchased by the bulb's power in kW: 40 kWh / 0.01 kW = 4000 hours.

Therefore, the light bulb can stay on for 4000 hours on a $2.00 budget given the energy cost of $0.05 per kWh, which corresponds to answer choice C.

User Ganesh Rengarajan
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