neco 2021 data_processing | Essay

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Question 1 View Details
A small retail shop records its daily sales transactions in a handwritten ledger. The owner plans to adopt a computer‑based system to handle this information more efficiently.
Question Parts
(a)
State the four main stages of the data processing cycle and give a brief explanation of each stage.
(b)
Distinguish between data and information, providing one specific example of each from the shop’s operations.
(c)
Discuss two advantages and two disadvantages of using a computerised data‑processing system for the shop.
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Question 2 View Details
The table below shows the monthly sales performance of a retailer for the first quarter of the year. Month | Units Sold | Selling Price per unit (₦) --- | --- | --- January | 120 | 2,500 February | 150 | 2,600 March | 130 | 2,550
Question Parts
(a)
Calculate the total revenue earned in each month.
(b)
Determine the average monthly revenue for the quarter.
(c)
Compute the percentage change in revenue from January to February.
(d)
The retailer wishes to know the average selling price per unit for the quarter, weighted by the number of units sold each month. Calculate this weighted average price.
(e)
Identify one possible source of error in the data presented and suggest a practical method to reduce this error.
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Question 3 View Details
A school ICT project requires the collection, entry, processing and presentation of survey data. The project follows the standard Data Processing Cycle.
Question Parts
(a)
List the four main stages of the Data Processing Cycle and give a brief description of each.
(b)
When the student uses a spreadsheet formula to calculate the average score of the survey, which stage of the cycle is being performed? Explain why this stage is critical to the overall process.
(c)
The estimated times for each stage of the project are: Input – 12 minutes, Processing – 8 minutes, Output – 5 minutes, Storage – 3 minutes. Compute the total time taken from the start of input to the completion of storage. Show your working.
(d)
Suggest two practical measures that could reduce the total processing time by at least 20 % without compromising data integrity. For each measure, estimate the new time for the affected stage and recalculate the total time to demonstrate that the required reduction is achieved.
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Question 4 View Details
A company needs to store a customer database on a disk. Each customer record occupies 150 bytes and the database contains 10 000 records. The disk uses a block size of 4 KB and has an average seek time of 8 ms with a transfer rate of 200 KB s⁻¹.
Question Parts
(a)
Differentiate between sequential file organization and random (direct) access file organization, focusing on how records are stored and retrieved.
(b)
Calculate the minimum number of disk blocks required to store the 10 000 records, assuming no wasted space within a block.
(c)
Estimate the average time to read a single record from the file when it is stored using (i) sequential organization and (ii) random access organization. Show all steps and state any assumptions you make.
(d)
Based on your calculations, recommend the most suitable file organization for this database and justify your recommendation.
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Question 5 View Details
A university maintains a relational database to store information about its students, courses, lecturers and the results of examinations.
Question Parts
(a)
Write a relational algebra expression that retrieves the names of students who are enrolled in **every** course taught by Lecturer Dr. Okoro.
(b)
The current design of the database includes the following relations (attributes shown in brackets): • STUDENT(SID, SName, Dept) • LECTURER(LID, LName, Dept) • COURSE(CID, CTitle, LID) • ENROLL(SID, CID, Grade) Discuss whether each relation is in Third Normal Form (3NF). If any relation is not in 3NF, show how it can be decomposed to achieve 3NF.
(c)
During the end‑of‑semester period, the registrar performs a transaction that changes the Grade of a student for a particular course from ‘B’ to ‘A’. Explain the ACID properties of this transaction and why each is important in the context of the university database.
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Question 6 View Details
Consider the following combinational circuit with three binary inputs A, B and C and a single output Z. The truth table for Z is given below.
Question Parts
(a)
Using a Karnaugh map, obtain the minimal Sum‑of‑Products (SOP) Boolean expression for Z.
(b)
Implement the minimal SOP expression using only NAND gates. Provide a schematic description of the resulting circuit.
(c)
If each NAND gate has a propagation delay of 2 ns, calculate the worst‑case propagation delay from the inputs (A, B, C) to the output Z for the implemented circuit. Explain how the choice of NAND‑only implementation influences the delay compared with a mixed‑gate implementation.
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Question 7 View Details
A multinational corporation suffered a data breach when an employee unintentionally downloaded a malicious attachment, leading to the exposure of personal data of thousands of customers. The incident raised concerns about the ethical conduct of staff, the adequacy of the company's security measures, and the legal responsibilities under Nigerian cyber law.
Question Parts
(a)
Identify three core ethical principles that were violated by the employee’s action and briefly explain how each principle was breached.
(b)
Suggest two technical security measures that the corporation should implement to prevent a similar breach in the future. Justify each measure with a short explanation of how it mitigates the risk.
(c)
Discuss the trade‑off between user convenience and security when implementing two‑factor authentication (2FA) in a large organisation.
(d)
Evaluate the legal implications of the breach under the Nigerian Cybercrimes (Prohibition, Prevention, etc.) Act 2015. Mention at least two provisions that may apply and the possible penalties for the corporation.
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Question 8 View Details
In many rural areas of Nigeria, small‑holder farmers are beginning to adopt Internet of Things (IoT) devices to monitor soil moisture, temperature and pest activity. While these technologies promise higher yields, farmers often face practical constraints.
Question Parts
(a)
Explain how IoT can improve the productivity of small‑holder farms. Give at least three specific ways the technology can be used.
(b)
Identify two major challenges that limit the adoption of IoT devices by these farmers and briefly describe why each is a barrier.
(c)
Propose a feasible ICT intervention that could overcome one of the challenges identified in part (b). Outline the required resources (hardware, training, support) and the expected outcome for the farmers.
(d)
Using the following data, perform a simple cost‑benefit analysis to decide if the intervention in part (c) is economically viable: - Cost of the solar data hub (including hardware and installation) per farmer: ₦150,000. - Training and support cost per farmer: ₦30,000. - Average annual revenue from the farm before IoT: ₦500,000. - Expected increase in revenue per season due to better decisions: 20%. - The hub has a useful life of 5 seasons. Calculate the total net benefit over the hub’s life and state whether the investment is justified.
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