The alternatives shown are to be compared on the basis of their present worth values. At an interest rate of 10% per year, the values of n that you should use in the uniform series factors to make a correct comparison by the present worth method are:

first costs annual operating cost, salvage value, $ life years -50000 -10000 13000 3 B -90000 4000 15000 6 B.-151027.4 A.-175306.4 A.-151127.4 B.-175316.4.BO A.-151027.4 B.-175306.4.CO