In a replacement analysis for a vacuum seal on a spacecraft the following data are known about the challenger. The initial investment is $11,000 , there is no annual maintenance cost for the first 3 years , however , it will be $3,000 in each of years four and five , and then $5,000 in the sixth year and increasing by $2,000 each year thereafter . The market value at the end of the year k is 50% of year k-1 at all times , the MARR is 15% per year.(Hint:After a certain year,the EUAC will keep increasing.)

a) What is the economic life of this challenger?

b) What is the EUAC corresponding to the economic life in part a ?