Practice neco data_processing 2022 Past Questions

Question 1 View Details

A company maintains 10,000 employee records, each occupying 150 bytes. To support fast retrieval by employee ID and also to generate reports sorted by department, the company considers three file organisations: 1. Sequential file (no index). 2. Indexed sequential file with a primary index on employee ID. The block size is \(512\) bytes and each index entry occupies \(12\) bytes. 3. Direct (hash) file with 2,000 buckets. Assuming the data occupy the same amount of storage in all three cases, which file organisation provides the minimum total storage (data plus index) while satisfying both the fast‑ID retrieval and the sorted‑by‑department reporting requirements?

A. Direct

B. Hybrid

Correct C. Indexed sequential

D. Sequential

Correct Answer: C

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Question 2 View Details

State the three basic stages of data processing in the correct order.

A. Input, Output, Processing

B. Processing, Input, Output

Correct C. Input, Processing, Output

D. Collection, Processing, Output

Correct Answer: C

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Question 3 View Details

Simplify the Boolean expression \(F = (A + B')(C'D + AB) + A'BC\) and give the minimum number of two‑input NAND gates required to implement the simplified expression.

A. 19

B. 23

C. 25

Correct D. 21

Correct Answer: D

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Question 4 View Details

Define the terms "data" and "information" as used in data processing.

A. Data are raw numbers; information is processed numbers that have meaning.

Correct B. Data are raw facts; information is processed data that has meaning.

C. Data are raw facts; information is unprocessed data without meaning.

D. Data are processed facts; information is raw data that has meaning.

Correct Answer: B

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Question 5 View Details

In a relational database table, what is a primary key?

Correct A. A field (or combination of fields) that uniquely identifies each record in the table

B. A field that determines the order in which records are displayed

C. A field that stores the most frequently accessed data in the table

D. A field that links the table to external databases

Correct Answer: A

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Question 6 View Details

A class of 30 students has an average test score of \(68\). After a retest, 5 students each improve their scores by \(4\) points while the other students' scores remain unchanged. What is the new average score of the class? Express your answer as a mixed number.

A. 68\frac{3}{4}

B. 69\frac{2}{3}

C. 68\frac{1}{3}

Correct D. 68\frac{2}{3}

Correct Answer: D

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Question 7 View Details

In a typical data processing cycle, the stages are: (1) data collection, (2) data storage, (3) data processing, (4) data analysis, and (5) presentation. A company collects sales data daily, stores it in a database, then runs a program that cleans the data before generating monthly reports. However, errors are still appearing in the reports because some invalid entries are not being detected. At which stage of the data processing cycle should data validation be performed to prevent these errors, and why?

A. During the storage stage, because validating data when it is saved prevents corrupted records from being processed later.

B. During the analysis stage, because verifying data just before interpretation catches any remaining issues before presentation.

C. During the collection stage, because checking data as it is gathered ensures errors are caught before storage.

Correct D. During the processing stage (data cleaning), because validation at this point removes erroneous entries before analysis and presentation.

Correct Answer: D

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Question 8 View Details

A shop records the number of items sold each day for a week as follows: Monday \(15\), Tuesday \(22\), Wednesday \(18\), Thursday \(20\), Friday \(25\), Saturday \(19\), and Sunday \(23\). What is the total number of items sold during the week?

Correct A. 142

B. 138

C. 140

D. 152

Correct Answer: A

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Question 9 View Details

Consider a relational table STUDENT_ENROLLMENT with attributes: StudentID, Name, Dept, CourseCode, CourseName, Instructor. Each student can enrol in multiple courses, each course can have multiple students, and each course is taught by a single instructor.\n\n(a) List the functional dependencies that hold in this table.\n(b) Identify the candidate key(s).\n(c) State whether the table is in Second Normal Form (2NF). Provide a brief justification.

A. FDs: StudentID → Name, Dept; Instructor → CourseName; (StudentID, CourseCode) → all attributes. Candidate key: StudentID. The table is in 2NF because all non‑key attributes depend on the whole key.

Correct B. FDs: StudentID → Name, Dept; CourseCode → CourseName, Instructor; (StudentID, CourseCode) → all attributes. Candidate key: (StudentID, CourseCode). The table is not in 2NF because non‑key attributes depend on parts of the composite key.

C. FDs: StudentID → Name, Dept, CourseCode; CourseCode → CourseName; (StudentID, CourseCode) → Instructor. Candidate key: StudentID. The table is in 2NF as there are no partial dependencies.

D. FDs: StudentID → Name; CourseCode → CourseName, Instructor; Instructor → Dept. Candidate key: (StudentID, Instructor). The table is not in 2NF because Instructor depends only on CourseCode.

Correct Answer: B

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Question 10 View Details

A bag contains red, blue, and green balls in the ratio \(2:3:5\). Assuming the bag holds the minimum whole number of balls consistent with this ratio, four balls are drawn at random without replacement. What is the probability that exactly two of the drawn balls are red? Express your answer as a reduced fraction.

Correct A. 2/15

B. 4/15

C. 1/5

D. 3/20

Correct Answer: A

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Question 11 View Details

The company has identified three threats to its information assets:\n\n- Threat A: probability \(0.02\), potential loss \u20A6 500,000.\n- Threat B: probability \(0.05\), potential loss \u20A6 300,000.\n- Threat C: probability \(0.01\), potential loss \u20A6 800,000.\n\nThree possible security controls are available, but only one can be implemented:\n\n* Control X reduces the probability of Threat A by \(40\%\) and Threat B by \(20\%\).\n* Control Y reduces the probability of Threat C by \(50\%\) and Threat B by \(30\%\).\n* Control Z reduces the probability of Threat A by \(25\%\) and Threat C by \(25\%\).\n\nAssuming the reductions are applied to the original probabilities, which control results in the lowest expected annual loss? State your answer as "Control X", "Control Y" or "Control Z".

A. Control Z

Correct B. Control Y

C. Control X

D. Control W

Correct Answer: B

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Question 12 View Details

A file of size \(12{,}800\) bytes is to be stored on a disk whose block size is \(512\) bytes. Pointer size is \(4\) bytes. Compare the total disk space required (in bytes) for each of the following allocation methods:\n\n1. Contiguous allocation.\n2. Linked allocation (each block stores a 4‑byte pointer).\n3. Indexed allocation with a single index block.\n\nWhich method uses the least total disk space? Give your answer as "Contiguous", "Linked" or "Indexed".

Correct A. Contiguous

B. Indexed

C. Linked

D. Hybrid

Correct Answer: A

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Question 13 View Details

A small business is considering purchasing a computer system that costs \u20A6 1,200,000. The system has an estimated useful life of 4 years and a salvage value of \u20A6 200,000 at the end of year 4. Operating costs are \u20A6 80,000 per year. The system is expected to generate an additional revenue of \u20A6 350,000 each year. Using a discount rate of 10 % per annum, should the business purchase the system? State "Yes" if the net present value is positive, otherwise "No".

A. Yes, purchase the system

B. Yes, the NPV is positive

C. Yes

Correct D. No

Correct Answer: D

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Question 14 View Details

The organisation requires that a symmetric encryption key must resist a brute‑force attack for at least 10 years. An attacker can test \(10^{12}\) keys per second. What is the minimum key length in bits that satisfies this requirement? Give the smallest integer number of bits.

Correct A. 69

B. 68

C. 64

D. 70

Correct Answer: A

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Question 15 View Details

In a spreadsheet, cell B2 contains a salesperson's monthly sales amount (in Naira). The commission structure is:\n\n- 5 % on the first \u20A6 200,000,\n- 7 % on the next \u20A6 300,000 (i.e., from \u20A6 200,001 to \u20A6 500,000),\n- 10 % on any amount above \u20A6 500,000.\n\nWrite the Excel formula (using IF and arithmetic operators) that calculates the total commission in cell C2 based on the value in B2. Provide the formula exactly as it should be entered.

A. =IF(B2<=200000,0.05*B2,IF(B2<=500000,0.05*200000+0.06*(B2-200000),0.05*200000+0.07*300000+0.10*(B2-500000)))

Correct B. =IF(B2<=200000,0.05*B2,IF(B2<=500000,0.05*200000+0.07*(B2-200000),0.05*200000+0.07*300000+0.10*(B2-500000)))

C. =IF(B2<200000,0.05*B2,IF(B2<=500000,0.05*200000+0.07*(B2-200000),0.05*200000+0.07*300000+0.10*(B2-500000)))

D. =IF(B2<=200000,0.05*B2,IF(B2<=500000,0.05*200000+0.07*(B2-200000),0.05*200000+0.07*300000+0.08*(B2-500000)))

Correct Answer: B

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Question 16 View Details

Consider the five steps of a data processing cycle labelled as follows: Input (\(I\)), Process (\(P\)), Output (\(O\)), Storage (\(S\)) and Retrieval (\(R\)). The following ordering constraints must be satisfied: \(I\) must occur before \(P\); \(P\) must occur before both \(O\) and \(S\); and \(S\) must occur before \(R\). No other ordering restrictions apply. How many distinct linear orders of the five steps satisfy all the constraints?

A. 6

B. 5

Correct C. 3

D. 4

Correct Answer: C

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Question 17 View Details

A student records the number of books in each class and then adds these numbers together to find the total number of books. Which step of the data processing cycle is the student performing at this stage?

Correct A. Process

B. Organize

C. Collect

D. Analyze

Correct Answer: A

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Question 18 View Details

A household is comparing three smartphone models (A, B and C) using weighted criteria. The attributes and their values are: \(\text{Price (\,\text{₦})}\): A = 50,000; B = 45,000; C = 55,000. \(\text{Battery life (hours)}\): A = 20; B = 18; C = 22. \(\text{Storage (GB)}\): A = 64; B = 128; C = 32. The decision‑making weights are: price 0.4 (lower price is better), battery life 0.35 (higher is better) and storage 0.25 (higher is better). For each attribute, compute a normalized score between 0 and 1 using the formula \(S = \frac{\text{max} - \text{value}}{\text{max} - \text{min}}\) for price and \(S = \frac{\text{value} - \text{min}}{\text{max} - \text{min}}\) for battery and storage. Then calculate the overall utility \(U = 0.4S_{price}+0.35S_{battery}+0.25S_{storage}\). Which phone model should be chosen based on the highest utility?

A. Phone A

Correct B. Phone B

C. Phone D

D. Phone C

Correct Answer: B

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Question 19 View Details

Given the Boolean expression \(F = (A + \overline{B})(\overline{A} + B + C)\), simplify it to a minimal sum‑of‑products form and then determine the output value of \(F\) when \(A=1\), \(B=0\) and \(C=1\).

A. 3

B. 0

Correct C. 1

D. 2

Correct Answer: C

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Question 20 View Details

A data entry operator inputs 200 records. During processing, 5% of the records are found to contain errors. The operator decides to correct only the erroneous records and then re‑process them. If correcting each erroneous record takes 2 minutes and re‑processing each record takes 1 minute, how many minutes of total processing time are saved compared with re‑processing all 200 records?

A. 150

B. 180

Correct C. 170

D. 160

Correct Answer: C

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Question 21 View Details

A company's data processing system follows the steps: input, processing, storage, output, and control. During a month, 10,000 sales records are entered. The control step detects and discards \(2\%\) of the records as erroneous before processing. The processing step compresses the remaining data by \(30\%\) before it is stored. Assuming no further loss, what percentage of the original 10,000 records is present in the final output report?

A. 29.4\%

B. 68\%

C. 68.0\%

Correct D. 68.6\%

Correct Answer: D

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Question 22 View Details

Consider a relation \(R(A,B,C,D)\) with the functional dependencies \(A \rightarrow B\), \(B \rightarrow C\) and \(A \rightarrow D\). Determine the highest normal form that \(R\) satisfies and list all candidate keys of \(R\).

Correct A. 2NF; candidate key: A

B. 2NF; candidate key: B

C. 1NF; candidate key: A

D. 3NF; candidate key: A

Correct Answer: A

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Question 23 View Details

A file contains 2,000 records, each 512 bytes long, stored on a disk with a block size of 4 KB. The disk rotates at 7,200 rpm, has an average seek time of 5 ms and a transfer rate of 100 MB/s.\n\n(a) Compute the time to read the entire file sequentially (include one initial seek and average rotational latency).\n(b) Compute the time to read a single record randomly (include seek, average rotational latency and transfer of one record).\n(c) What is the difference in milliseconds between the sequential and random read times?

A. 8.3 ms

Correct B. 10.2 ms

C. 15.0 ms

D. 12.5 ms

Correct Answer: B

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Question 24 View Details

The five steps of the data processing cycle take the following times for a particular transaction: input = 2 s, processing = 5 s, storage = 3 s, output = 2 s, control = 1 s. The control step runs concurrently with the processing step, overlapping exactly 1 second of processing time. What is the total time required to complete the cycle for this transaction?

A. 11 s

B. 13 s

C. 10 s

Correct D. 12 s

Correct Answer: D

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Question 25 View Details

A spreadsheet records monthly sales (in units) for three products over six months as follows:\n\n\begin{tabular}{c|cccccc}\nMonth & Jan & Feb & Mar & Apr & May & Jun \\ \hline\nProduct A & 120 & 150 & 130 & 160 & 140 & 155 \\nProduct B & 80 & 95 & 85 & 90 & 100 & 110 \\nProduct C & 200 & 210 & 190 & 205 & 195 & 215 \\n\end{tabular}\n\n(a) What is the total sales for the six‑month period?\n(b) Which product contributes more than \(40\%\) of the total sales?\n(c) Using the formula \(\frac{S_{last}-S_{first}}{S_{first}}\times100\%\), where \(S_{first}\) and \(S_{last}\) are the sales of the product identified in part (b) in January and June respectively, compute its average monthly growth rate (in %).

A. Total sales = 2630 units; product = C; growth = 8.2\\%

B. Total sales = 2700 units; product = A; growth = 7.5\\%

C. Total sales = 2600 units; product = B; growth = 6.8\\%

Correct D. Total sales = 2630 units; product = C; growth = 7.5\%

Correct Answer: D

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