First, let me say that the exam prep school i'm working with is not good and I have found another.
While Ive gotten some value from their materials, the material is rife with typos, formatting errors and is based on 2005/2008 NEC. Boo. I also have extreme strengths in some areas and weakness' in others due to the unorthodox method I entered and worked in the field. Note that the CSLB has accepted my application irregardless. I'm weak in safety regs, big jobsite protocols and employment labor laws, etc.
However, I'm very strong technically, so I'm mystifed by this question:




Question 10: 
In a school, twenty 75watt incandescent lights were replaced with twenty 20watt fluorescent bulbs. If they pay $0.10/KWH, how much will they save in a year?







$100 



$275 



$375 



$475

By my calculations, the existing light array is 1.5kwh so it costed $.15 per hr so yearly costs were $.15 x24x365 assuming lights on 24x7. = $1314 per year
The New array is .4kw so costs .4x $.10 per hr or $.04 so yearly costs are $.04 x24x365=$350 a year
~ Approx 1/4 power, 1/4 the cost, so the savings should be greater then any of those values unless I'm making a mistake. Any help would be appreciated. Thx, Humble Hank.
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