Neco Model Questions Vol1 2021 Agricultural Science Question 3

A 150‑ha forest can be planted with species A and species B. Species A grows 2.5 m yr\(^{-1}\) from an initial height of 1.5 m and is harvested after 10 years, yielding 0.8 m³ of timber per hectare for each metre of height above 1.5 m. Species B grows 1.8 m yr\(^{-1}\) from an initial height of 0.8 m and is harvested after 15 years, yielding 0.6 m³ ha\(^{-1}\) per metre of height above 0.8 m. Timber prices are ₦250 m\(^{-3}\) for species A and ₦300 m\(^{-3}\) for species B. Soil suitability limits the area planted to species A to at most 70 % of the total forest. Assuming successive rotations over a 30‑year planning horizon (i.e., after each harvest the same species is replanted on the same area), determine the proportion of the forest that should be allocated to each species to maximise total revenue, and compute that maximum total revenue (in ₦).