Light emitting diode $($LEDs$)$ light bulbs have become required in recent years, but do they make financial sense? Suppose a typical $60-$watt incandescent light bulb costs $$\mathrm{.}52$ and lasts for $1,000$ hours. A $15-$watt LED, which provides the same light, costs $$3\mathrm{.}75$ and lasts for $12,000$ hours. A kilowatt hour of electricity costs $$\mathrm{.}128.$ A kilowatt$-$hour is $1,000$ watts for $1$ hour. However, electricity costs actually vary quite a bit depending on location and user type. An industrial user in