You Are Thinking of Making Your Mansion More Energy Efficient

You are thinking of making your mansion more energy efficient by replacing some of the light bulbs with compact fluorescent bulbs, and insulating part or all of your exterior walls. Each compact fluorescent light bulb costs $4 and saves you an average of $2 per year in energy costs, and each square foot of wall insulation costs $1 and saves you an average of $0.20 per year in energy costs. Your mansion has 200 light fittings and 2,000 sq. ft. of uninsulated exterior wall. To impress your friends, you would like to spend as much as possible, but save no more than $600 per year in energy costs (you are proud of your large utility bills) . How many compact fluorescent light bulbs and how many square feet of insulation should you purchase How much will you save in energy costs per year ?

A) 100 fluorescent light bulbs, 2,000 square feet of insulation should be purchased, and $600 per year will be saved
B) 200 fluorescent light bulbs, 1,000 square feet of insulation should be purchased, and $600 per year will be saved
C) 200 fluorescent light bulbs, 0 square feet of insulation should be purchased, and $800 per year will be saved
D) 0 fluorescent light bulbs, 2,000 square feet of insulation should be purchased, and $2,000 per year will be saved
E) no solution