7 Consider the investment projects in Table P7, all of which have a four-year in- vestment life. TABLE P7 Project's Cash Flow ($) A B C D 0 -$2,500 -$3,500 -$2,800 -$2,300 1 $0 $1,600 -$1,800 -$1,000 2 $0 $2,800 -$900 $1.900 3 $0 $3.500 $4.500 $2,300 4 $6,200 $2,200 $4,500 $1,500 (a) What is the payback period of each project? (b) What is the discounted payback period at an interest rate of 15% for each project