12-26. Refer to Example 12-4. After additional research, the range of probable useful lives has been narrowed down to the following three possibilities:

Useful Life, Years (N) p(N)

14 0.3 15 0.4 16 0.3 How does this affect E(PW) and SD(PW)? What are the benefits associated with the cost of obtaining more accurate estimates? (12.4)