neco 2025 data_processing | Essay

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Question 1 View Details
A class of 20 students sat for a mathematics test. Their scores (out of 100) are: 45, 52, 58, 61, 63, 65, 68, 70, 71, 73, 74, 76, 78, 80, 82, 84, 86, 88, 90, 95.
Question Parts
(a)
Construct a grouped frequency distribution for the scores using class intervals of 10 (i.e., 40‑49, 50‑59, …, 90‑99).
(b)
Using the distribution obtained in (a), calculate the mean, median, modal class and range of the scores.
(c)
Comment on the shape of the distribution by comparing the mean and median. State whether the distribution is approximately symmetric, positively skewed or negatively skewed.
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Question 2 View Details
A small retail shop sells three products – A, B and C. The following information relates to the most recent month of operation:
Question Parts
(a)
Calculate the total revenue generated by each product and the overall revenue for the month.
(b)
Determine the contribution margin per unit for each product and the total contribution from each product. Identify which product contributes the most towards covering the shop’s fixed costs of ₦20,000.
(c)
The shop wishes to increase its profit by 20 % in the next month while keeping unit prices and variable costs unchanged. Assuming the increase in profit will be achieved solely by selling more units of the product that contributes the most (identified in part b), calculate the minimum additional number of units of that product that must be sold.
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Question 3 View Details
A small retail shop uses a computer system to manage its inventory of goods. The system records purchases, sales, and generates reports for the shop owner.
Question Parts
(a)
State the five stages of the Data Processing Cycle and give a brief description of the purpose of each stage.
(b)
For the inventory system described above, indicate which stage of the Data Processing Cycle is responsible for:
() Verification that the quantity entered for a new stock item is a positive integer.
() Generation of a printed report of items that are below the reorder level.
(c)
The shop manager proposes adding a feedback stage after the output stage to improve the accuracy of the inventory records. Discuss two possible forms of feedback that could be incorporated and explain how each would enhance the system.
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Question 4 View Details
A secondary school keeps a digital file of the examination results of 500 students. Each student record contains the following fields: - Admission number (8 characters) - Name (30 characters) - Three subject scores, each stored as a 2‑byte integer. The file is stored on a disk whose block size is 512 bytes.
Question Parts
(a)
Calculate the size in bytes of a single student record. Show the working.
(b)
If the file is organised as a sequential file, determine: (i) the number of disk blocks required to store the whole file, (ii) the amount of internal fragmentation (unused space) in the last block.
() Number of disk blocks required.
() Internal fragmentation in the last block.
(c)
The school is considering converting the file to an Indexed Sequential Access Method (ISAM) with a primary index that stores the admission number and the block address of each record. Each index entry occupies 10 bytes (8 for the admission number and 2 for the block address). (i) Calculate the total size of the index. (ii) Determine the total storage (data + index) required, assuming the same 512‑byte block size. (iii) Briefly state one advantage of using this indexed organisation over the simple sequential file.
() Total size of the index.
() Total storage required (data + index).
() One advantage of the indexed organisation.
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Question 5 View Details
A small retail store maintains information about its products, suppliers and purchase orders. The relational tables are defined as follows: - **Products**(ProductID, ProductName, UnitPrice, SupplierID) - **Suppliers**(SupplierID, SupplierName, ContactNo) - **PurchaseOrders**(OrderID, OrderDate, SupplierID) - **OrderDetails**(OrderID, ProductID, Quantity) Each product is supplied by exactly one supplier, a supplier may supply many products, each purchase order is placed with a single supplier, and an order can contain many different products. The store wishes to improve data integrity and automate some controls. Answer the following questions:
Question Parts
(a)
State the highest normal form (up to BCNF) that each of the four tables currently satisfies. Justify your answer for each table.
(b)
Write an SQL query that lists the names of suppliers who have supplied more than three **different** products in the last 30 days, assuming the current date is 2025‑06‑30. Show the logical steps you used to obtain the query.
(c)
The store wants to ensure that the total monetary value of each purchase order ( Σ UnitPrice × Quantity ) never exceeds ₦500,000. Propose a trigger (in pseudo‑SQL) that prevents the insertion of an OrderDetails row which would cause the total to go over this limit. Explain briefly how the trigger works.
(d)
Explain two possible consequences for the store if a transaction that updates OrderDetails violates the ACID properties.
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Question 6 View Details
A digital system requires a three‑variable Boolean function \(F(A,B,C)\) that is true for minterms 1, 2, 5, 6 and 7 (binary representations of the minterm numbers are shown below).
Question Parts
(a)
Draw the Karnaugh map for \(F\) and obtain the minimal sum‑of‑products (SOP) expression. Show the grouping you used.
(b)
Implement the minimal expression using only NAND gates. Provide a clear description of the gate connections (no diagram required).
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Question 7 View Details
A small retail business, GreenMart, uses a computer system to store personal details of its customers, including names, phone numbers, and purchase histories. The owner wants to improve the ethical handling and security of this data. GreenMart processes about 500 transactions each day, each transaction generating 2 MB of data. The owner plans to implement a weekly backup strategy that uses an initial full backup followed by incremental backups, assuming that on average only 10 % of the data changes each subsequent day.
Question Parts
(a)
Identify and briefly explain three major ethical issues that arise from the collection and storage of customers' personal data.
(b)
Propose a comprehensive security policy for GreenMart that includes at least two technical controls and two administrative controls. For each control, explain how it mitigates a specific risk identified in part (a).
(c)
Calculate the approximate amount of storage required for the weekly backup, assuming the first day of the week is a full backup of that day's data and each subsequent day only backs up the 10 % of new data generated that day.
(d)
Discuss why regular security audits are essential for GreenMart and how they support ethical compliance with the issues raised in part (a).
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Question 8 View Details
Mobile banking has become a dominant ICT service in Nigeria, offering convenient financial transactions through smartphones. Consider the following hypothetical data on the number of active mobile‑banking users in five regions at the start of 2025:
Question Parts
(a)
Explain how ICT, specifically mobile banking, has transformed personal banking in Nigeria. Cite two distinct services that illustrate this transformation.
(b)
The number of users in the five regions are: Region A – 150 000, Region B – 80 000, Region C – 45 000, Region D – 30 000, Region E – 20 000. If each region experiences a 12 % increase in users over the next year, calculate the new number of users for each region and state the overall percentage increase in the total user base.
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