Neco Model Questions Vol1 2022 Agricultural Science Question 1

A farmer harvests 10,000 kg of cassava roots with an initial moisture content of 70 % (wet basis). He uses a solar dryer in which the moisture content (M(t)) (as a fraction) decreases according to the differential equation \(\frac{dM}{dt} = -k\bigl(M-M_a\bigr)\) where the ambient moisture (M_a = 0.05) and the constant (k = 0.03\,\text{h}^{-1}\). He wishes to dry the roots to a final moisture content of 20 % (wet basis).\n(a) Calculate the drying time required (in hours) to reach the target moisture.\n(b) Determine the total weight of the roots after drying.\n(c) If during storage the dried roots lose 2 % of their dry matter each month, find the net total weight after three months of storage (assume moisture remains at 20 %).