Neco 2024 Agricultural Science Question 32

A farmer harvested 10\,000\,kg of cassava roots with an initial moisture content of 60\% (wet basis). The desired final moisture content for safe storage is 20\% (wet basis). A drying facility can operate at two temperature settings:\n\n- 40\,°C, drying rate 0.8 percentage‑points of moisture per hour, energy cost N10 per hour, no quality penalty.\n- 55\,°C, drying rate 1.5 percentage‑points per hour, energy cost N25 per hour, and a quality penalty that reduces the market price of the dried product by 5\% for each hour of drying above 6\,h, up to a maximum total reduction of 30\%.\n\nThe market price of dried cassava (at 20\% moisture) is N30 per kg. Water removed can be sold at N0.5 per kg. The farmer must have the dried product ready within 30\,hours of drying. Determine the combination of operating temperatures (hours at 55\,°C followed by hours at 40\,°C) that maximises net revenue, and state the maximum net revenue (to the nearest Naira).