information on four investment proposals is given below: investment proposal a b c d investment required $ (280,000 ) $ (140,000 ) $ (50,000 ) $ (780,000 ) present value of cash inflows 393,900 192,800 78,100 1,038,100 net present value $ 113,900 $ 52,800 $ 28,100 $ 258,100 life of the project 5 years 7 years 6 years 6 years required: 1. compute the project profitability index for each investment proposal. (round your answers to 2 decimal places.) 2. rank the proposals in terms of preference.