Two bridge designs have been proposed for the new interstate highway to cross Rio de Lubbock. A bridge constructed from wood will cost $6,000 and will last for eight years. A bridge constructed from steel will cost $11,000 and will last for twenty years. Either bridge will have a zero salvage value at the end of its life. Use an interest rate of 8 percent and decide whether the increased life of the steel bridge justifies its increased cost.