1. The alternatives shown are to be compared on the basis of their present worth values. At an interest rate of 8% 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 S life years A -50000 -10000 13000 6 B -90000 -4000 15000 3 (A-88836.4 B.-158573.6) OB (A-88036.4 B.-158573.6) C (A-89036.4 B.-158073.6)