5. Lorraine can select from two nutrient injection systems for her cottage industry of hydroponic tomato and lettuce greenhouses. (a) Use an AW relation to determine the minimum number of hours per year to operate the pumps that will justify the Auto Green system, if the MARR is 10% per year. (b) which pump is economically better if it operates 7 hours per day, 365 days per year? (number of rebuilds could be fractional) Nutra Jet (N) Auto Green (A) Initial cost, Life, years Rebuild cost,S Time before rebuild, annually or minimum hours Cost to operate, S per hour 4,000 -1,000 2.000 1.00 10,300 -2.200 8,000 0.90