Posted by Mike on Tuesday, December 7, 2010 at 12:02pm.
Consumers pay for electricity by the kilowatthour (the amount of electricity used by a 1,000watt appliance in one hour). If electricity costs 10cents per kilowatthour, what is the cost of running a 100watt lamp for
1. 1 hour?
2. 24 hours?
3. 1 year?

math  MathMate, Tuesday, December 7, 2010 at 1:45pm
100 watt lamp running for 1 hour uses
100/1000 kilowatts for 1 hour, so it will cost
(100/1000)*1 hour *10 cents
= 1 cent.
I'll leave #2 and #3 to you. 
math  Steve, Tuesday, December 7, 2010 at 2:08pm
2. $0.24
3. $87.60 
math  MathMate, Tuesday, December 7, 2010 at 8:12pm
Correct!