Please help!

srhly

A 78.9 W, 107.3 V light bulb is plugged into a 59.2 V outlet. If energy costs 4.9 cents/kW*h, how much does it cost per month (30 days) to leave the light bulb turned on? Answer in units of cents.

This is what I did:

(78.9W/107.3V)(59.2V)(24hours)(30days)(4.9cents/kW*h)(1kW/1000W)

I got 153.58 cents. I know the answer is incorrect, but where did I go wrong?

zwtipp05

P=VI
V=IR

Calculate the resistance, then find the current at the new voltage. Then use conversion factors to get your price.

srhly

Thanks, that helped!