A facility uses lights for 5,500 hrs/yr. Presently, they use fluorescent lighting and pay $11,550/yr for electric power for these lights. Some bulbs burn out each year, and, on average, the annual replacement cost for the existing bulbs is $570/yr. A contractor recommends replacing all the fluorescent tubes with equivalent LED tubes, and it will costs $6,868 to install the new bulbs. The LED tubes use less energy, so only need $6,188/yr to operate, and have a longer life, but cost more per bulb, and on average the annual replacement costs will be $760/yr. If the plant switches to LED tubes, what is the SPP for the investment? Give your answer to two decimal places.