A
railway track will be used for 15 years. During the construction of
the railway track line, either type A or type B ties may be used.
Type A ties have an installed cost of $6 and a 10-year life; type B
will cost $4.50 with a 6-year life. If at the end of 15 years the
ties used have a remaining useful life of at least 4 years they
will be used elsewhere for a different project and can fetch a
salvage value of $3 each. Any ties that are taken off after the end
of their life or if it is very near to the end of its life to be
used elsewhere, then, it can be sold for $0.50 each. Give the most
cost effective plan for the 15 year analysis period using NPW
method at 8% interest.