Question 84675This question is from textbook Mathematics A Quantitative Reasoning Approach 
:  For some reason these problems keep tripping me up...please help...Thanks!
 
Compact Flourescent Light Bulbs. 
You replace a 100-watt light bulb with a 25-watt compact fluorescent bulb.  Over a 10,000-hr life, how much energy, in kilowatt hours, do you save?  If electricity costs .08 cents per kilowatt-hour how much money do you save? 
This question is from textbook Mathematics A Quantitative Reasoning Approach 
 Answer by liz_gcmama(8)      (Show Source): 
You can  put this solution on YOUR website! Compact Flourescent Light Bulbs. 
You replace a 100-watt light bulb with a 25-watt compact fluorescent bulb.  Over a 10,000-hr life, how much energy, in kilowatt hours, do you save?  If electricity costs .08 cents per kilowatt-hour how much money do you save?
 
1000watt-hours to the kilowatt-hour (that is, one kilowatt drawn constantly over the course of an hour) 
One 100 watt globe uses 0.1 kilowatt-hours per hour. 
One 25 watt globe uses 0.025 kilowatt-hours per hour.
 
In 10,000 hours, how much will each globe use? 
10000*0.1=1000   
The 100 watt globe uses 1000 kilowatt-hours in its life.
 
10000*0.025=250 
The 25 watt globe uses 250 kilowatt-hours in its life.
 
1000-250=750. 
750 kilowatt-hours would be saved.
 
750*0.08=60 
Based on the information given, 60 cents would be saved.  However, I would guess that the amount is 8 cents or 0.08 dollars per kilowatt (a more realistic figure), giving the answer of 6000 cents or $60.00.
 
 
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