physics
posted by Micah
At 7.35 cents per kiloway hr, A. what does it cost to operate a 10.0 hp motor for 8.00 hr? B. What does it cost to leave a 75W light burning 24 hr a day?

Steve
Just multiply by conversion factors to change from what you have to what you want:
You have
10.0 hp * 8.00 hr = 80.00 hphr * 0.0735$/kwhr = 1088.435 $hp/kw * 1.0 kw / 1.341 hp = $811.66 
drwls
A. I get a different answer
10 hp = 7460 W = 7.46 kW
Energy used (in kWh) = 7.46*8 = 59.68
Cost = (59.68 kWh)*(0.0735 $/kWh)
= $4.38 
Elvis Rabohale
A.
1 hp = 0.745699872 kilowatts
10hp X 0.745699872 X 8 = 59.66 kWh
Cost = 59.66 X 0.0735 = R4.38472
B.
75W/1000 X 24 X 0.0735 = R0.1323
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