Answer to Problem # 17:

12 lamps  x  75 watts   x   10 hr.  x   9 cents    x    kw.  =    ? cents
                         lamp                              kw x hr.    1000 watts

12 x  75  x  10  x   9 cents    =     9000    x    9 cents     = 
                   1000                                        1000

        9  x  9 cents   =    81 cents (ANSWER) 


 
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