An electric cooperative is considering the use of a concrete electric pole in the expansion of its power distribution lines. A concrete pole costs 180,000 each and will last 20 years. The company is presently using creosoted wooden poles which cost 120,000 per pole and will last 10 years. If money is worth 12 percent, which pole should be used? 

Assume annual taxes amount to 1 percent of first cost and zero salvage value in both cases.