Practice neco model questions vol1 agricultural_science 2024 Past Questions

Question 1 View Details

A farmer has 180 chickens each weighing an average of 2.2 kg. To treat an outbreak of coccidiosis, a medication requires a dosage of 0.5 ml per kilogram of body weight per day for 5 days. The medication is sold in 250 ml bottles costing ₦3,200 each. After treatment, a withdrawal period of 7 days prevents the sale of eggs; the farm produces 120 eggs per day, each sold at ₦25. Calculate the total cost incurred, including the cost of medication and the loss of egg revenue during the withdrawal period. Give your answer in naira, rounded to the nearest naira.

A. ₦30,400

Correct B. ₦33,800

C. ₦35,600

D. ₦31,200

Correct Answer: B

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Question 2 View Details

A 2‑hectare pond is stocked with catfish at a density of 5,000 fingerlings per hectare. The growth of an individual fish (in kilograms) after t days follows the model \(W(t)=0.001\,t^{2}\). The farmer will harvest when the average fish weight reaches 0.8 kg. Mortality occurs at a constant rate of 0.1 % per day, acting cumulatively. The market price is ₦1,200 per kilogram of fish, and the feed conversion ratio is 1.5 kg feed per kilogram of fish produced; feed costs ₦150 per kilogram. Assuming no other costs, determine the expected net profit from the harvest. Give your answer in naira, rounded to the nearest naira.

A. ₦6,950,000

Correct B. ₦7,582,380

C. ₦7,200,000

D. ₦8,120,000

Correct Answer: B

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Question 3 View Details

In a cattle herd, disease Z has a prevalence of 5 %. A diagnostic test for the disease has a sensitivity of 90 % and a specificity of 95 %. If a randomly selected animal tests positive, what is the probability that it is truly infected with disease Z? Express your answer as a percentage rounded to one decimal place.

A. 52.1 %

B. 35.4 %

C. 61.7 %

Correct D. 48.6 %

Correct Answer: D

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Question 4 View Details

A tractor with a 45 kW engine is used for ploughing. The required drawbar power is given by \(P = \dfrac{F \times v}{\eta}\), where \(F\) is the draft force in kN, \(v\) is the forward speed in m s⁻¹, and \(\eta = 0.85\) is the transmission efficiency. The draft force for the plough depends on soil moisture \(s\) (in %) as \(F = 2 + 0.04s\) (kN). The field has an average soil moisture of 20 % and the tractor moves at 5 km h⁻¹. The plough cuts a strip 2.5 m wide. The tractor's specific fuel consumption is 210 g kWh⁻¹ and diesel density is 0.85 kg L⁻¹. How many litres of diesel are required to plough a 10‑hectare field? Give your answer to two decimal places.

A. 10.23 L

B. 8.57 L

Correct C. 9.04 L

D. 7.89 L

Correct Answer: C

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Question 5 View Details

A farmer cultivates maize on 5 ha. The variable cost per hectare (in naira) depends on the expected yield \(Y\) (tonnes ha⁻¹) as \(C_v = 1500 + 200Y - 5Y^{2}\). Fixed costs for the whole farm amount to ₦10,000. The market price per tonne is a decreasing linear function of total production \(Q = 5Y\): \(P = 2000 - 20Q\) (naira per tonne). Determine the yield per hectare that maximises the farmer's profit and compute the maximum profit. Give the optimal yield to one decimal place (tonnes ha⁻¹) and the profit in naira, rounded to the nearest naira.

Correct A. Yield: 9.5 t ha⁻¹; Profit: ₦25,131

B. Yield: 8.0 t ha⁻¹; Profit: ₦20,000

C. Yield: 7.5 t ha⁻¹; Profit: ₦15,750

D. Yield: 10.2 t ha⁻¹; Profit: ₦30,500

Correct Answer: A

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Question 6 View Details

A farmer harvests maize with an initial moisture content of 25\% (wet basis). He stores the grain in a hermetic bag where the moisture content declines exponentially according to \(M(t)=M_{0}e^{-kt}\) with \(k=0.04\ \text{day}^{-1}\). The bag also halves the normal respiration rate, which would otherwise cause a dry‑matter loss of 0.2\% per day; thus the loss is 0.1\% per day. Safe storage requires the moisture content to be at most 15\% and the cumulative respiration loss not to exceed 5\% of the original dry weight. Determine the maximum whole number of days the farmer can store the maize before either condition is violated.

Correct A. 50

B. 45

C. 55

D. 60

Correct Answer: A

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Question 7 View Details

A farmer practices a three‑year rotation of maize, cowpea and fallow on a 1‑ha plot.\n\n- Maize yields 4 t ha⁻¹ and requires 120 kg N ha⁻¹.\n- Cowpea yields 1.5 t ha⁻¹, fixes 40 kg N ha⁻¹ and itself needs 20 kg N ha⁻¹.\n- The soil initially contains 30 kg N ha⁻¹. Any surplus N after a year remains in the soil for the next year (no loss).\n- Fertiliser N costs \(\text{₦}150\) per kg.\n- Market prices are \(\text{₦}250\) per kg of maize and \(\text{₦}180\) per kg of cowpea.\n\nAssuming no other costs, calculate the total net profit over the three‑year cycle per hectare.

Correct A. 1256500

B. 1300000

C. 1266500

D. 1246500

Correct Answer: A

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Question 8 View Details

In a tomato field the economic injury level (EIL) for whitefly is given by \(\text{EIL}=\dfrac{C}{V\times I\times D}\), where \(C\) is the cost of control per hectare, \(V\) is the market value per kilogram of tomato, \(I\) is the injury per whitefly (kg loss per whitefly per hectare) and \(D\) is the efficacy of the pesticide (proportion killed). The farmer can apply a pesticide that costs \(\text{₦}12,000\) per hectare and kills 80\% of the whitefly population. Tomato sells for \(\text{₦}150\) per kg and each whitefly causes a loss of \(0.02\) kg per hectare. The current whitefly density is 5,000 insects per hectare. Should the farmer apply the pesticide?

A. Maybe

Correct B. No

C. Probably

D. Yes

Correct Answer: B

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Question 9 View Details

A hand‑operated seed drill uses a lever that is 0.4 m long from the pivot to the point where the farmer applies effort. The seed hopper (load) exerts a weight of 30 N at a distance of 0.1 m from the pivot.\n\n(a) What is the minimum effort force the farmer must apply to lift the hopper?\n(b) If the farmer makes 0.5 lifting cycles per second, assuming the hopper is raised through a vertical distance equal to its radius (0.1 m) each cycle and neglecting friction, calculate the average power output in watts.

A. 6.0 N; 1.2 W

B. 9.0 N; 2.0 W

C. 5.0 N; 1.0 W

Correct D. 7.5 N; 1.5 W

Correct Answer: D

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Question 10 View Details

A 10‑ha wheat field normally yields 3 t ha⁻¹. Stripe rust has infected 20\% of the plants; each infected plant reduces the yield by 0.5 kg. A fungicide costing \(\text{₦}8,000\) per ha reduces the incidence by 75\% (i.e., to 5\%). Wheat sells for \(\text{₦}120\) per kg. Should the farmer apply the fungicide, and if so, by how much will net profit increase (in ₦)?

A. Yes; profit increases by ₦900,000

Correct B. Yes; profit increases by ₦820,000

C. No; profit decreases by ₦50,000

D. Yes; profit increases by ₦750,000

Correct Answer: B

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Question 11 View Details

A farmer has 3 ha of land. He plants maize on 2 ha at a spacing that gives 55,000 plants per hectare. The remaining 1 ha is used for a mixed crop: sorghum occupies 60 % of that hectare and is sown at 40,000 plants per hectare, while cowpea occupies the remaining 40 % and is sown at 25,000 plants per hectare. How many total plants are in the whole field?

A. 138000

B. 124000

Correct C. 144000

D. 150000

Correct Answer: C

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Question 12 View Details

A farmer harvests 10,000 kg of cassava roots with an initial moisture content of 60 % (wet basis). He can choose between two post‑harvest options:\n\nOption A: Dry the roots in a solar dryer that reduces the moisture to 12 % in 48 hours. The dryer costs ₦150 per day.\n\nOption B: Store the fresh roots in a ventilated store for 10 days. During storage the moisture loss is 0.5 % of the total weight per day, but after 10 days 20 % of the roots rot and become unsellable. The storage cost is ₦80 per day.\n\nDry roots sell for ₦30 per kilogram of dry weight, while fresh roots sell for ₦12 per kilogram of wet weight. Which option gives the higher net profit, and what is that profit (in naira) for the chosen option?

A. Option B, ₦95000

Correct B. Option A, ₦136064

C. Option A, ₦119700

D. Option B, ₦90400

Correct Answer: B

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Question 13 View Details

A farmer has 40 ha of land to allocate between millet and groundnut. Fixed cost for the season is ₦50,000. Variable costs are ₦30,000 per hectare for millet and ₦45,000 per hectare for groundnut. Expected yields are 2.5 t ha⁻¹ for millet and 1.2 t ha⁻¹ for groundnut. Market prices are ₦120,000 t⁻¹ for millet and ₦200,000 t⁻¹ for groundnut. However, if the farmer plants more than 20 ha of millet, the market price of millet falls by 10 % (to ₦108,000 t⁻¹). Determine the allocation of hectares to millet and groundnut that maximizes profit and state the maximum profit (in naira).

A. 30 ha millet, 10 ha groundnut; profit ₦8420000

B. 20 ha millet, 20 ha groundnut; profit ₦7200000

C. 35 ha millet, 5 ha groundnut; profit ₦9000000

Correct D. 40 ha millet, 0 ha groundnut; profit ₦9550000

Correct Answer: D

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Question 14 View Details

A tractor has an engine power of 60 kW and runs at 1800 rpm. It drives a PTO shaft that operates at 540 rpm. Assuming no losses, calculate the torque transmitted to the PTO shaft (in N·m). The implement attached to the PTO requires a pulling force of 8 kN applied at a wheel radius of 0.4 m. The PTO torque is transmitted to the wheel through a gear train with a ratio of 4 : 1 (torque is multiplied by 4). What is the minimum overall efficiency (as a percentage) that the power‑transmission system must have to meet the required pulling force? Provide the PTO torque (rounded to the nearest N·m) and the minimum efficiency (to one decimal place).

A. 1000 N·m, 70.0%

B. 950 N·m, 68.5%

Correct C. 1062 N·m, 75.3%

D. 1120 N·m, 80.0%

Correct Answer: C

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Question 15 View Details

A 5‑ha tomato field contains 20,000 plants per hectare. At the start of the season 2 % of the plants are infected with a fungal disease. Each infected plant creates 0.8 new infections per week. The crop is harvested after 6 weeks. Without any control, each infected plant reduces the yield by 0.5 kg. The market price is ₦120,000 per tonne. A fungicide costing ₦5,000 per hectare can be applied at the beginning of week 3; it reduces the weekly infection rate by 60 % for the remaining weeks. Assuming no other losses, should the farmer apply the fungicide? Calculate the net profit (in naira) for the whole field under (i) no treatment and (ii) treatment, and indicate which option is more profitable.

A. Do not apply fungicide; profit with treatment ₦16794200, without treatment ₦13918800

B. Apply fungicide; profit with treatment ₦16794200, without treatment ₦13000000

Correct C. Apply fungicide; profit with treatment ₦16794200, without treatment ₦13918800

D. Apply fungicide; profit with treatment ₦15000000, without treatment ₦13918800

Correct Answer: C

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Question 16 View Details

A farmer grows maize. Fixed costs are \(150{,}000\) Naira per season and the variable cost is \(30{,}000\) Naira per tonne. The selling price per tonne is \(55{,}000\) Naira for the first 10 tonnes, but for each tonne above 10 the price falls by \(500\) Naira because of market saturation. How many tonnes must be produced and sold to achieve a profit of at least \(120{,}000\) Naira?

Correct A. 11

B. 12

C. 9

D. 10

Correct Answer: A

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Question 17 View Details

A farm has \(20\) hectares of grazing land. The land can sustainably support \(0.8\) Animal Units (AU) per hectare. An adult cattle equals \(1\) AU and a calf equals \(0.3\) AU. The farmer already keeps \(12\) adult cattle and wants to add as many calves as possible without exceeding the land's carrying capacity. How many calves can be added?

A. 12

B. 14

Correct C. 13

D. 11

Correct Answer: C

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Question 18 View Details

A state has \(150\) villages, each with an average of \(200\) farmers. Extension agents are to hold group meetings so that every farmer attends at least one meeting in a month. Each meeting can accommodate up to \(25\) farmers. Twenty percent of the villages are remote; a meeting in a remote village consumes two working days, while a meeting in a normal village consumes one working day. Each extension agent works \(20\) days per month. What is the minimum number of extension agents required to cover all farmers within the month?

Correct A. 72

B. 68

C. 80

D. 96

Correct Answer: A

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Question 19 View Details

A farmer harvests \(10{,}000\) kg of fresh cassava roots whose initial moisture content is \(45\)% (wet basis). He wants to dry the roots to a final moisture content of \(12\)% (wet basis). The drying process removes water at a rate of \(0.8\) kg water per hour for every \(100\) kg of fresh cassava being dried, and each dryer can handle at most \(2{,}000\) kg of fresh cassava at a time. Assuming any number of identical dryers can be used simultaneously, determine the minimum number of dryers required and the total drying time (in hours) needed to reach the target moisture content for the whole batch.

A. 6 dryers and 40.2 hours

Correct B. 5 dryers and 46.9 hours

C. 5 dryers and 55.0 hours

D. 4 dryers and 52.3 hours

Correct Answer: B

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Question 20 View Details

A mature mango tree adds \(10\) kg of dry matter each year. Dry matter is \(45\)% carbon by weight, and each kilogram of carbon corresponds to \(3.67\) kg of \(CO_2\). Estimate how many kilograms of \(CO_2\) are sequestered by the tree in one year.

A. 4.5 kg CO2

Correct B. 16.5 kg CO2

C. 16.2 kg CO2

D. 18.35 kg CO2

Correct Answer: B

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Question 21 View Details

Consider a lake fish population that follows the logistic growth model with constant harvest: \[\frac{dN}{dt}= r N\left(1-\frac{N}{K}\right)-H,\] where \(r = 0.4\ \text{yr}^{-1}\), \(K = 20\,000\) fish and the initial stock is \(N_0 = 8\,000\) fish. (a) Determine the maximum constant harvest \(H_{\max}\) (in fish per year) that allows the population to persist. (b) Find the constant harvest level \(H\) (as a percentage of \(H_{\max}\)) that gives two positive equilibrium stock sizes, one at 8 000 fish and the other at 12 000 fish. (c) State which of these equilibria is stable and which is unstable.

A. H_max = 1,800 fish/yr; H = 1,728 fish/yr (96 % of H_max); 8,000‑fish equilibrium unstable, 12,000‑fish equilibrium stable

B. H_max = 2,000 fish/yr; H = 1,800 fish/yr (90 % of H_max); 8,000‑fish equilibrium unstable, 12,000‑fish equilibrium stable

Correct C. H_max = 2,000 fish/yr; H = 1,920 fish/yr (96 % of H_max); 8,000‑fish equilibrium unstable, 12,000‑fish equilibrium stable

D. H_max = 2,500 fish/yr; H = 2,400 fish/yr (96 % of H_max); 8,000‑fish equilibrium stable, 12,000‑fish equilibrium unstable

Correct Answer: C

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Question 22 View Details

An insect pest causes a daily yield loss of 0.05 % of the expected harvest of 2 000 kg ha⁻¹. The market price of the crop is ₦200 per kg. A pesticide costs ₦1 500 ha⁻¹ to apply and kills 80 % of the pest population instantly. Using the economic injury level (EIL) formula \[EIL = \frac{C}{V \times I \times K},\] where \(C\) is control cost, \(V\) is market value per kg, \(I\) is injury per pest (kg loss), and \(K\) is the proportion killed, determine the minimum pest density (number of pests per hectare) at which pesticide application is justified. Round up to the nearest whole pest.

A. 12 pests per hectare

Correct B. 10 pests per hectare

C. 8 pests per hectare

D. 15 pests per hectare

Correct Answer: B

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Question 23 View Details

Soil tests show that the available phosphorus (P) in a field is 8 mg kg⁻¹, while the agronomic target is 20 mg kg⁻¹. One kilogram of single superphosphate (SSP) contains 20 % P₂O₅ by weight. To raise the soil P level, 1 mg kg⁻¹ of available P corresponds to an application of 2 kg ha⁻¹ of P₂O₅. Assuming a 15 % loss of applied P₂O₅ due to fixation, calculate the amount of SSP (kg ha⁻¹) that should be applied to meet the target.

A. 100 kg per hectare (approximately)

B. 160 kg per hectare (approximately)

C. 120 kg per hectare (approximately)

Correct D. 141 kg per hectare (approximately)

Correct Answer: D

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Question 24 View Details

A soil sample contains 30 % sand, 45 % silt and 25 % clay. Using the USDA soil texture triangle, identify the textural class of the soil.

A. loamy sand

Correct B. silty clay loam

C. clay loam

D. sandy loam

Correct Answer: B

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Question 25 View Details

The volume growth of a forest stand (in cubic metres per hectare) is described by \(V(t)=200\bigl(1-e^{-0.05t}\bigr)\), where \(t\) is the age in years. The stand is currently 30 years old. The timber price is ₦2 000 m⁻³, the re‑planting cost is ₦20 000 ha⁻¹, and the discount rate is 5 % per annum. Using the Faustmann formula for the present value of an infinite series of rotations, \[PV(T)=\frac{P\,V(T)\,e^{-iT}-C}{1-e^{-iT}},\] where \(P\) is price, \(C\) is re‑planting cost and \(i\) is the discount rate, determine the rotation age \(T\) (in whole years) that maximises the present value. Provide the optimal \(T\) and the corresponding maximum present value (rounded to the nearest thousand naira).

A. Optimal rotation age = 35 years; maximum present value ≈ ₦60,000 per hectare

B. Optimal rotation age = 40 years; maximum present value ≈ ₦55,000 per hectare

C. Optimal rotation age = 25 years; maximum present value ≈ ₦58,000 per hectare

Correct D. Optimal rotation age = 30 years; maximum present value ≈ ₦63,000 per hectare

Correct Answer: D

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