Electicity and cost -PS

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Electicity and cost -PS

by manoj0609 » Fri Jan 02, 2009 2:56 am
The cost of 1 unit of electricity during a 4 year period is given below. Year 1, $1 per unit. Year 2, $1.5 per unit. Year 3, $1.2 per unit. Year 4, $2 per unit. If a factory spent equal dollars each year for electricity what was the average cost of a unit of electricity during the 4 year period?

Can somebody pls help me
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by ronniecoleman » Fri Jan 02, 2009 3:57 am
total cost / total units


let x be the dollars spend each year:

Average cost = 4x/( x/1+ x/1.5 + x /1.2 + x/2)


Average cost = 4/ ( 1+ 2/3+ 5/6+ 1/2)
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by siddhu » Wed Sep 15, 2010 9:57 pm
(120*1)+(80*1.5)+(100*1.2)+(60*2)/(120+80+100+60) answer is 1.33