Practice waec model questions vol1 agricultural_science 2024 Past Questions

Question 1 View Details

A farmer uses a hand hoe that tills 1.2 m² per minute. The hoe becomes dull after each hour of continuous work, reducing its efficiency by 20 % for the next hour unless it is sharpened. Sharpening restores the original efficiency and takes 10 minutes. The farmer must till a field of 0.18 hectare (1 ha = 10 000 m²). Assuming the farmer sharpens the hoe only when necessary and works in whole‑hour blocks, what is the minimum total time (in hours) required to till the whole field, including sharpening time?

A. 30

B. 32

C. 28

Correct D. 29

Correct Answer: D

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Question 2 View Details

In a fish pond, the catfish population N (in number of fish) follows the logistic growth equation dN/dt = r N (1 - N/K) with intrinsic growth rate r = 0.3 month⁻¹ and carrying capacity K = 2000 fish. Each month, after the natural growth, a fixed proportion h of the population is harvested. Determine the harvesting proportion h (as a percentage) that maximises the sustainable monthly yield, and compute that maximum yield (number of fish harvested per month).

A. h = 12% and maximum yield = 140 fish per month

Correct B. h = 15% and maximum yield = 150 fish per month

C. h = 10% and maximum yield = 120 fish per month

D. h = 20% and maximum yield = 200 fish per month

Correct Answer: B

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Question 3 View Details

An agricultural extension officer has 120 days in a year to conduct training sessions for three farmer groups: rice, maize and cassava. Each rice session lasts 3 days and reaches 25 farmers; each maize session lasts 4 days and reaches 30 farmers; each cassava session lasts 2 days and reaches 20 farmers. Policy requires at least 20 % of the total days to be spent on rice sessions. The officer must hold at least 8 rice sessions, 6 maize sessions and 5 cassava sessions. How many sessions of each crop should be organised to maximise the total number of farmers reached, and what is that maximum number?

A. Rice = 8, Maize = 7, Cassava = 30; Maximum farmers reached = 1090

Correct B. Rice = 8, Maize = 6, Cassava = 36; Maximum farmers reached = 1100

C. Rice = 9, Maize = 6, Cassava = 33; Maximum farmers reached = 1085

D. Rice = 8, Maize = 6, Cassava = 35; Maximum farmers reached = 1085

Correct Answer: B

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Question 4 View Details

A farmer plans to grow tomatoes on 2 ha. Fixed costs (land preparation, irrigation) amount to ₦200 000, and variable costs are ₦120 000 per hectare. Expected yield is 25 000 kg per hectare. The market price is expected to be ₦50 per kg, but if total production exceeds 50 000 kg the price falls by 10 %. What is the minimum market price per kilogram (after any reduction) that the farmer must obtain to break even?

A. ₦9.20 per kg (approximately)

B. ₦7.50 per kg (approximately)

C. ₦8.00 per kg (approximately)

Correct D. ₦8.80 per kg (approximately)

Correct Answer: D

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Question 5 View Details

A combine harvester requires a draw‑bar power of 150 kW. The available tractor has a rated engine power of 200 kW and a transmission efficiency of 85 %. Its engine runs at 1800 rpm and delivers power to the draw‑bar through a hydraulic system operating at 250 bar pressure and a flow rate of 80 L min⁻¹. (a) Can the tractor supply the required draw‑bar power? (b) If the harvester operates for 5 hours at the required power and the engine's specific fuel consumption is 210 g kWh⁻¹, how many litres of diesel will be consumed? (Assume diesel density = 0.85 kg L⁻¹.)

Correct A. Yes; approximately 185.3 litres

B. Yes; approximately 210.8 litres

C. Yes; approximately 170.2 litres

D. Yes; approximately 160.5 litres

Correct Answer: A

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Question 6 View Details

A soil sample contains 40% sand, 35% silt and 25% clay. According to the USDA soil texture triangle, what is the texture class of this soil?

A. Silty loam

B. Clay loam

C. Loam

Correct D. Sandy loam

Correct Answer: D

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Question 7 View Details

A poultry farm started the month with 800 chickens. During the month, 48 chickens died showing signs of Newcastle disease and 12 chickens were culled after testing positive. Twenty chickens recovered after treatment. Calculate the mortality rate (deaths only) as a percentage of the initial flock and state whether the outbreak meets the WAEC definition of an epidemic (mortality > 5%). Express your answer as "X% - Yes" or "X% - No".

Correct A. 6% - Yes

B. 6% - No

C. 7% - Yes

D. 5% - No

Correct Answer: A

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Question 8 View Details

A farmer wants to plant a short‑duration maize variety that takes exactly 90 days from sowing to harvest. The national market price for maize falls by 20% in months when the national harvest peaks, which are March and September. The farmer's region experiences two rainy seasons that start in June and December; the crop must be harvested before the start of the next rainy season. Assuming the farmer can sow in any month, in which month should the farmer sow the maize to maximise revenue?

A. February

Correct B. January

C. December

D. March

Correct Answer: B

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Question 9 View Details

A maize field is infested with stem borer insects. The initial population is 200 insects per hectare and it grows exponentially at 25% per week. The economic threshold level (ETL) is 800 insects per hectare. A pesticide, applied only once at the end of a week, instantly reduces the population by 60% (i.e., leaves 40% of the insects). The farmer will apply the pesticide the first week the population would exceed the ETL if no control were used. After how many weeks from the start will the population first exceed the ETL?

A. 14

B. 9

C. 12

Correct D. 11

Correct Answer: D

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Question 10 View Details

A dairy farm has 50 lactating cows. Each cow gains 0.5 kg of body weight per day during early lactation. The feed conversion ratio (FCR) for weight gain is 1.8 kg dry‑matter feed per kg of gain. The farm wants to provide enough concentrate feed to meet the weight‑gain requirement for a 30‑day period, while a basal roughage supplies 60 % of the total dry‑matter intake (DMI). If the concentrate feed contains 90 % dry matter, how many kilograms of concentrate feed should be purchased for the 30‑day period? Round to the nearest kilogram.

Correct A. 600

B. 540

C. 750

D. 900

Correct Answer: A

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Question 11 View Details

A farmer rears broiler chickens that start at a live weight of 0.10 kg. During the first 21 days the birds gain an average of 45 g per day and have a feed conversion ratio (FCR) of 1.8. After day 21 the diet is changed; the daily gain falls to 30 g but the FCR improves to 1.6. If the market weight required is 2.00 kg per bird, calculate the total amount of feed (in kilograms, to two decimal places) that must be given to each bird for the whole growth period.

Correct A. 3.23 kg

B. 3.45 kg

C. 2.87 kg

D. 3.01 kg

Correct Answer: A

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Question 12 View Details

A batch of 500 kg fresh cassava roots contains 60 % moisture (wet basis). After peeling and slicing, the chips are dried in a solar dryer. For the first period, while the moisture content is above 30 % (wet basis), the drying rate is constant at 2.5 kg of water removed per hour. Once the moisture content reaches 30 %, the drying rate drops to 1.2 kg of water per hour. Determine (a) the total drying time required to reduce the moisture content to 12 % (wet basis) and (b) the total energy needed for the whole drying operation, assuming the latent heat of vaporisation of water is 2260 kJ kg⁻¹. Express the drying time in hours (one decimal place) and the energy in kilojoules (nearest whole number).

A. 140.2 h, 640,000 kJ

B. 125.8 h, 610,000 kJ

Correct C. 134.4 h, 616,364 kJ

D. 130.5 h, 590,000 kJ

Correct Answer: C

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Question 13 View Details

A lake stocked with tilapia follows the logistic growth model \(\frac{dN}{dt}=rN\left(1-\frac{N}{K}\right)\) where the intrinsic growth rate \(r=0.6\) year⁻¹ and the carrying capacity \(K=8000\) fish. A constant annual harvest \(H\) (fish year⁻¹) is imposed. Determine the maximum constant harvest that can be sustained indefinitely without driving the population to extinction (i.e., the maximum sustainable yield). Also give the equilibrium population size that corresponds to this harvest.

A. Maximum sustainable harvest = 800 fish/year; equilibrium population = 2000 fish

B. Maximum sustainable harvest = 1000 fish/year; equilibrium population = 5000 fish

Correct C. Maximum sustainable harvest = 1200 fish/year; equilibrium population = 4000 fish

D. Maximum sustainable harvest = 1500 fish/year; equilibrium population = 3000 fish

Correct Answer: C

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Question 14 View Details

State the soil microbial process that converts atmospheric nitrogen (N₂) into ammonia (NH₃) usable by plants.

A. Nitrification

B. Denitrification

C. Ammonification

Correct D. Nitrogen fixation

Correct Answer: D

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Question 15 View Details

A goat weighing 45 kg shows clinical signs suggestive of contagious caprine pleuropneumonia (CCPP). The recommended treatment is oxytetracycline administered intramuscularly at 10 mg per kg of body weight once daily for 5 consecutive days. Calculate the total amount of oxytetracycline (in grams) required for the complete treatment course.

A. 2.5 g

B. 2.0 g

C. 2.75 g

Correct D. 2.25 g

Correct Answer: D

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Question 16 View Details

A farmer intends to control early blight on a 2.5‑ha tomato field. The recommended rate of the copper‑based fungicide is 2.5 kg of active ingredient per hectare. The product sold contains 200 g of active ingredient per litre of formulation. (i) Calculate the total volume of the product that must be mixed for the whole field. (ii) If the farmer decides to split the application into three equal sprays, how many litres of product are required for each spray? Give your answers to two decimal places.

A. Total volume = 33.33 L; each spray = 11.11 L

Correct B. Total volume = 31.25 L; each spray = 10.42 L

C. Total volume = 28.75 L; each spray = 9.58 L

D. Total volume = 30.00 L; each spray = 10.00 L

Correct Answer: B

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Question 17 View Details

An agricultural extension officer must train 120 farmers from three villages: Village A (50 farmers), Village B (40 farmers) and Village C (30 farmers). Each training session can accommodate at most 25 farmers and lasts 2 days, 4 hours per day. The officer can conduct at most two sessions per calendar day. (i) What is the minimum number of calendar days required to complete the training? (ii) Assuming the officer is paid ₦1 500 per day and receives a travel allowance of ₦200 for each village visited on a training day, determine the minimum total cost of the training programme. Show how the sessions should be scheduled to achieve this minimum cost.

A. Minimum days = 2; Minimum total cost = ₦4 200

B. Minimum days = 3; Minimum total cost = ₦5 500

C. Minimum days = 4; Minimum total cost = ₦6 400

Correct D. Minimum days = 3; Minimum total cost = ₦5 100

Correct Answer: D

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Question 18 View Details

A farmer needs to lift a 150 kg sack of grain from ground level to a height of 0.5 m. He can use either (a) a class‑1 lever with an effort arm of 0.6 m and a load arm of 0.20 m, or (b) a block‑and‑tackle system that provides an ideal mechanical advantage of 4. (i) For each device, calculate the effort force required to lift the sack (use g = 9.8 m s⁻²). (ii) For each device, determine the distance the farmer's hand must move to achieve the 0.5 m lift. (iii) Which device requires the smaller effort, and what are the corresponding effort force and hand‑movement distance? Give answers to two decimal places.

A. Lever is better; effort = 294.00 N; hand movement = 1.50 m

B. Block and tackle is better; effort = 400.00 N; hand movement = 2.00 m

Correct C. Block and tackle is better; effort = 367.50 N; hand movement = 2.00 m

D. Block and tackle is better; effort = 367.50 N; hand movement = 1.50 m

Correct Answer: C

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Question 19 View Details

A wheat field is affected by a rust fungus whose infection cycle lasts 10 days from spore germination to production of new spores. A fungicide applied remains effective for exactly 7 days. The farmer can only spray on days that are multiples of 3 (i.e., day 3, 6, 9, 12, …) counted from the first appearance of spores. (i) How many sprays are required to prevent any new spore production during a 30‑day period, assuming the first spore appearance occurs on day 0? (ii) On which days should the farmer apply the sprays to achieve this protection? Provide the days as numbers.

A. Two sprays; apply on days 6 and 24

B. Three sprays; apply on days 3, 9, and 21

Correct C. Two sprays; apply on days 3 and 18

D. One spray; apply on day 3

Correct Answer: C

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Question 20 View Details

A farmer has 10 ha of land to allocate between maize and soybeans. The profit (in naira) from each crop is given by \[\pi_m = \bigl(p_m\,y_m - C_m\bigr)A_m,\qquad \pi_s = \bigl(p_s\,y_s - C_s\bigr)A_s,\] where \(A_m\) and \(A_s\) are the areas (ha) planted to maize and soybeans respectively (\(A_m+A_s=10\)). The parameters are: - Maize: price \(p_m = 45{,}000\) ₦ ton⁻¹, yield \(y_m = 2.5 - 0.1A_m\) ton ha⁻¹, total cost per ha \(C_m = 10{,}000 + 2{,}000A_m\) ₦. - Soybeans: price \(p_s = 60{,}000\) ₦ ton⁻¹, yield \(y_s = 1.8 - 0.05A_s\) ton ha⁻¹, total cost per ha \(C_s = 8{,}000 + 1{,}500A_s\) ₦. Determine the allocation of land (values of \(A_m\) and \(A_s\) to two decimal places) that maximises total profit \(\Pi = \pi_m+\pi_s\), and state the maximum profit (rounded to the nearest naira).

A. Allocate 5.00 ha to maize and 5.00 ha to soybeans; maximum profit ≈ ₦730,120

Correct B. Allocate 4.20 ha to maize and 5.80 ha to soybeans; maximum profit ≈ ₦744,688

C. Allocate 4.80 ha to maize and 5.20 ha to soybeans; maximum profit ≈ ₦738,900

D. Allocate 3.75 ha to maize and 6.25 ha to soybeans; maximum profit ≈ ₦712,430

Correct Answer: B

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Question 21 View Details

A soil sample contains 40% sand, 35% silt and 25% clay. According to the USDA soil texture triangle, what is the textural class of this soil?

A. Silt loam

Correct B. Loam

C. Clay loam

D. Sandy loam

Correct Answer: B

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Question 22 View Details

A farmer feeds 50 kg of a concentrate containing 20 % protein to a flock of 20 chickens for 30 days. Each chicken gains 1.2 kg and after this period each chicken weighs 1.5 kg. The farmer now wants the average live weight to reach 2.5 kg, assuming the feed conversion ratio (FCR) remains the same. How many additional kilograms of concentrate will be required for the whole flock?

A. 50 kg

B. 38.5 kg

Correct C. 41.7 kg

D. 45.0 kg

Correct Answer: C

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Question 23 View Details

Which process in the nitrogen cycle converts atmospheric nitrogen (N₂) into ammonia (NH₃)?

A. Nitrification

B. Denitrification

C. Ammonification

Correct D. Nitrogen fixation

Correct Answer: D

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Question 24 View Details

A maize field of 2.5 ha is infested with stem borer. The recommended pesticide dosage is 0.75 L per ha of a formulation that contains 200 g L⁻¹ of active ingredient. The farmer decides to apply the pesticide in two equal splits 15 days apart. (a) What volume of pesticide solution should be mixed for each application? (b) If the harvested grain weight is 5 000 kg per ha, does the total amount of active ingredient applied stay within the maximum residue limit of 0.02 mg kg⁻¹ (assume 100 % of the active ingredient remains on the grain)?

A. 1.875 L each; residue within the 0.02 mg\/kg limit

B. 0.9375 L each; residue within the 0.02 mg\/kg limit

Correct C. 1.875 L each; residue exceeds the 0.02 mg/kg limit

D. 0.9375 L each; residue exceeds the 0.02 mg\/kg limit

Correct Answer: C

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Question 25 View Details

The volume (V, in m³ ha⁻¹) of a teak stand is modelled by the quadratic equation V = 0.4 t² + 3 t + 30, where t is the age in years. The current annual increment (CAI) for a given year t is the increase in volume from the previous year, i.e., CAI(t) = V(t) - V(t‑1). The mean annual increment (MAI) at age t is MAI(t) = V(t)/t. Determine the age (in years, to one decimal place) at which MAI equals CAI.

Correct A. 9.2 years

B. 10.3 years

C. 7.6 years

D. 8.4 years

Correct Answer: A

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