Practice neco data_processing 2023 Past Questions

Question 1 View Details

If a class of $40$ students spends a total of $100$ hours per week on word processing and $72$ hours per week on spreadsheets, and the average total ICT usage per student (across word processing, spreadsheets and presentations) is $8.4$ hours per week, what is the average weekly time spent on presentations per student (in hours)?

A. 4.0

B. 4.2

Correct C. 4.1

D. 5.1

Correct Answer: C

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Question 2 View Details

A company is evaluating the adoption of two‑factor authentication (2FA). Without 2FA, the probability of a security breach in a year is $0.12$; with 2FA, the probability drops to $0.03$. Each breach costs the company $500{,}000$ naira. The annual cost of implementing 2FA is $C$ naira. What is the maximum value of $C$ (in naira) for which the expected annual cost with 2FA is lower than without it?

A. 15000

B. 30000

Correct C. 45000

D. 60000

Correct Answer: C

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Question 3 View Details

In the data processing cycle, the following processing times are recorded per 100 records: data entry $12$ minutes, data cleaning $5$ minutes, data processing $8$ minutes, data analysis $15$ minutes, and reporting $4$ minutes. For a batch of $500$ records, calculate the total processing time (in minutes) and identify which stage consumes the greatest proportion of the total time.

A. 210 minutes; analysis

B. 220 minutes; processing

Correct C. 220 minutes; analysis

D. 225 minutes; analysis

Correct Answer: C

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Question 4 View Details

A disk uses a block size of $4$ KB. Three files are stored using contiguous allocation: a text file of $9.3$ KB, an image file of $15.7$ KB, and a video file of $102.5$ KB. Determine the total number of blocks required to store all three files and the total wasted space (in KB) due to internal fragmentation.

A. 34 blocks, 5.5 KB

B. 32 blocks, 3.5 KB

Correct C. 33 blocks, 4.5 KB

D. 33 blocks, 5.0 KB

Correct Answer: C

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Question 5 View Details

A small business currently stores $500$ GB of data on local servers purchased for $150{,}000$ naira, with an annual maintenance cost of $20{,}000$ naira and straight‑line depreciation over 5 years. They are considering a cloud storage subscription costing $12{,}000$ naira per month for up to 1 TB. Data volume grows by $20\%$ each year. Assuming the data never exceeds 1 TB within the period, after how many whole years will the cumulative cost of cloud storage exceed that of local storage? Also, compute the cumulative cost of each option after 3 years.

Correct A. 2 years; local N300,000, cloud N432,000

B. 2 years; local N300,000, cloud N480,000

C. 2 years; local N250,000, cloud N432,000

D. 3 years; local N300,000, cloud N432,000

Correct Answer: A

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Question 6 View Details

The Boolean function $F(A,B,C)$ is true for minterms 1, 2, 5, 6 and 7 (where $A$ is the most‑significant variable).\n(a) Obtain the minimal sum‑of‑products expression for $F$.\n(b) If the circuit is to be realised using only two‑input NAND gates, what is the minimum number of NAND gates required?

Correct A. 7

B. 9

C. 6

D. 8

Correct Answer: A

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Question 7 View Details

Consider the four‑variable Boolean function $G(A,B,C,D)$ defined by the minterm list\n$G = \Sigma m(0,2,5,7,8,10,13,15)$\nwith don't‑care conditions at minterms 1, 3, 12 and 14.\nDetermine a minimal sum‑of‑products expression for $G$ and state the total number of literals in that expression.

A. 6

B. 3

C. 5

Correct D. 4

Correct Answer: D

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Question 8 View Details

The Boolean function $H$ is given by\n$H = (A + \overline{B}C)\,(\overline{A} + B + \overline{C})$.\nSimplify $H$ to a minimal sum‑of‑products form and, using only two‑input OR gates and NOT gates, find the minimum number of OR gates required to implement the function.

A. 5

Correct B. 6

C. 7

D. 8

Correct Answer: B

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Question 9 View Details

A student discovers that the school's login system stores user passwords in plain text. According to the NECO Computer Ethics and Security code, the student can:\n(i) ignore the problem,\n(ii) fix the code without informing anyone,\n(iii) report the vulnerability to the school's IT administrator, or\n(iv) sell the information to a third party.\nThe risk associated with the vulnerability is evaluated by the formula\n$\text{Risk} = \text{Likelihood} \times \text{Impact}$,\nwhere the Likelihood is rated 4 (on a scale of 1-5) because the flaw is known, and the Impact is rated 5 (scale 1-5) for a possible data breach.\nClassify the risk as Low (1-6), Medium (7-12) or High (13-25) and state the ethically appropriate action the student should take.

Correct A. Report the vulnerability to the school's IT administrator; the risk rating is High

B. Sell the information to a third party; the risk rating is High

C. Ignore the problem; the risk rating is Medium

D. Fix the code without informing anyone; the risk rating is Low

Correct Answer: A

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Question 10 View Details

A CSV file contains 250 rows, each row has 8 fields. If each field occupies on average 12 bytes, estimate the total file size in kilobytes (1 KB = 1024 bytes). Round your answer to the nearest whole kilobyte.

Correct A. 23

B. 25

C. 24

D. 22

Correct Answer: A

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Question 11 View Details

Given the Boolean expression $Z = (A + \overline{B}C)(\overline{A} + B + \overline{C})$, simplify it to a minimal sum‑of‑products (SOP) form and state the total number of literals in that minimal expression.

A. A\overline{B} + A\overline{C} + \overline{A}\overline{B}C; 7 literals

B. AB + A\overline{C} + \overline{A}B\overline{C}; 7 literals

Correct C. AB + A\overline{C} + \overline{A}\overline{B}C; 7 literals

D. AB + \overline{A}\overline{B}C; 5 literals

Correct Answer: C

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Question 12 View Details

An original 7‑bit data word is 1011010. Using even parity, determine the parity bit that must be appended. If the transmitted 8‑bit word received is 10110101, does the parity check indicate an error?

A. Parity bit = 1; error detected

Correct B. Parity bit = 0; error detected

C. Parity bit = 1; no error

D. Parity bit = 0; no error

Correct Answer: B

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Question 13 View Details

Consider the following sales data (in units) for three products over four months:\n\n| Month | Product A | Product B | Product C |\n| Jan | 120 | 80 | 200 |\n| Feb | 150 | 95 | 210 |\n| Mar | 130 | 110 | 190 |\n| Apr | 160 | 105 | 220 |\n\n1. Compute the total sales for each product over the four months.\n2. Compute the overall average sales per entry (i.e., total of all 12 numbers divided by 12).\n3. Identify which months have a combined total sales exceeding $150\%$ of that overall average.\n4. Write an Excel formula that, given a month's total sales in cell E2, returns "Yes" if it exceeds the $150\%$ threshold and "No" otherwise.

A. Product totals - A: 570, B: 390, C: 820; Overall average = 149; Months exceeding 150% threshold: Jan, Mar, Apr; Excel formula: =IF(E2>1.4*AVERAGE($E$2:$E$5),\"Yes\",\"No\")

Correct B. Product totals - A: 560, B: 390, C: 820; Overall average = 147.5; Months exceeding 150% threshold: Jan, Feb, Mar, Apr; Excel formula: =IF(E2>1.5*AVERAGE($E$2:$E$5),"Yes","No")

C. Product totals - A: 550, B: 400, C: 810; Overall average = 146; Months exceeding 150% threshold: Jan, Feb, Apr; Excel formula: =IF(E2>1.5*AVERAGE($E$1:$E$4),\"Yes\",\"No\")

D. Product totals - A: 560, B: 380, C: 830; Overall average = 148; Months exceeding 150% threshold: Feb, Mar, Apr; Excel formula: =IF(E2>1.5*AVERAGE(E2:E5),\"Yes\",\"No\")

Correct Answer: B

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Question 14 View Details

Given the CSV line: 12,"Smith, John",45, list the three fields extracted from this line.

A. 12 ; John, Smith ; 45

B. 12 ; Smith, John ; 54

Correct C. 12 ; Smith, John ; 45

D. None of the above

Correct Answer: C

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Question 15 View Details

A batch of 500 records is processed through three stages: Input ($0.2$ s per record), Processing ($0.5$ s per record), and Output ($0.1$ s per record). Input can overlap with Processing of the same or another record, but Output cannot overlap with any other stage. Calculate the total time required to process the entire batch.

A. 250.2 seconds

B. 300.7 seconds

Correct C. 300.2 seconds

D. 350.2 seconds

Correct Answer: C

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Question 16 View Details

A user has three types of media files: videos (12\,GB), photos (3\,GB) and documents (0.8\,GB). A compression algorithm reduces video size by 40\% and photo size by 25\% while documents remain unchanged. The user must back up the files for four weeks. In week\,1 a full backup of all compressed files is made. In each subsequent week the user adds new video content of 1.2\,GB and new photos of 0.3\,GB; after compression these additions become 0.72\,GB and 0.225\,GB respectively. The user can choose either (A) a full backup each week (storing all compressed files) or (B) an incremental backup (storing only the new compressed data each week). Assuming a 32\,GB external hard‑drive, which backup method uses less total storage after four weeks and by how many gigabytes? Provide the answer to two decimal places.

Correct A. Incremental backup; saves 27.92 GB

B. Full backup; saves 27.92 GB

C. Incremental backup; saves 25.00 GB

D. Full backup; saves 5.13 GB

Correct Answer: A

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Question 17 View Details

A disk uses a block size of 4\,KB. Three files need to be stored: File A = 9\,KB, File B = 15\,KB, File C = 7\,KB. Compare the total disk space required under (i) contiguous allocation, (ii) linked allocation (each block pointer occupies 4\,bytes), and (iii) one‑level indexed allocation where each file has its own index block (size = one block). Which allocation method uses the least total space?

A. Linked allocation

B. Indexed allocation

C. One‑level indexed allocation

Correct D. Contiguous allocation

Correct Answer: D

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Question 18 View Details

A class of 30 students obtained the following test scores (in marks): 10 students scored 45, 8 scored 55, 6 scored 65, 4 scored 75 and 2 scored 85. The teacher assigns grades as follows: A for $\ge 70$, B for 60-69, C for 50-59, D for $<50$. Calculate the percentage of students receiving each grade, the class mean, and the weighted median. State whether the mean is higher than the median.

Correct A. A:20%; B:20%; C:26.67%; D:33.33%; Mean=58.33; Median=55; Mean is higher than median.

B. A:20%; B:20%; C:30%; D:30%; Mean=58.33; Median=55; Mean is higher than median.

C. A:20%; B:20%; C:26.67%; D:33.33%; Mean=57.50; Median=55; Mean is higher than median.

D. A:20%; B:20%; C:26.67%; D:33.33%; Mean=58.33; Median=60; Mean is lower than median.

Correct Answer: A

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Question 19 View Details

A mobile data plan charges as follows: first 2\,GB at $\text{₦}500$ per GB, the next up to 5\,GB at $\text{₦}400$ per GB, and any usage beyond 7\,GB at $\text{₦}300$ per GB. Unused data from a month rolls over to the next month but only up to 3\,GB; any excess is forfeited. In month 1 the user consumes 6.5\,GB, in month 2 consumes 3.2\,GB, and in month 3 consumes 4.8\,GB. Determine the total amount paid over the three months and the amount of data rolled over at the end of month 3.

Correct A. Total paid = 4830 Naira; data rolled over = 2.2 GB

B. Total paid = 4520 Naira; data rolled over = 3.0 GB

C. Total paid = 5030 Naira; data rolled over = 1.8 GB

D. Total paid = 4670 Naira; data rolled over = 2.5 GB

Correct Answer: A

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Question 20 View Details

A small business records daily sales (in thousand Naira) for 15 days as follows: 12, 15, 9, 13, 14, 11, 16, 10, 13, 12, 14, 15, 9, 11, 13. Compute the mean, median, mode, population standard deviation and coefficient of variation (as a percentage). A competitor has a mean of 13\,k and a standard deviation of 1.2\,k. State whether the business's sales are more variable than the competitor's.

A. Mean=13.2k; Median=13k; Mode=13k; StdDev≈1.9k; CV≈14.4%; Sales are less variable than competitor.

B. Mean=12.47k; Median=13k; Mode=12k; StdDev≈2.5k; CV≈20%; Sales are more variable than competitor.

C. Mean=12.47k; Median=12k; Mode=13k; StdDev≈2.09k; CV≈16.8%; Sales are less variable than competitor.

Correct D. Mean=12.47k; Median=13k; Mode=13k; StdDev≈2.09k; CV≈16.8%; Sales are more variable than competitor.

Correct Answer: D

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Question 21 View Details

The company has two departments. The Employees table lists the salaries (in thousand naira) of eight employees as follows: 45, 55, 60, 70, 80, 90, 100 and 110. Employees 1‑4 are assigned to Department A whose budget is ₦300 000, and employees 5‑8 are assigned to Department B whose budget is ₦250 000. Let the uniform reduction factor be $r$ (where $0<r<1$). If the same percentage reduction is applied to every employee's salary so that the total salary paid by each department does not exceed its budget, what percentage reduction (to one decimal place) must be applied?

A. 37.8

B. 29.4

Correct C. 34.2

D. 31.5

Correct Answer: C

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Question 22 View Details

A user stores data that grows by 20\% each month, starting with 50 GB in month 0. A cloud provider charges per month as follows: the first 100 GB at ₦200 per GB, the next up to 500 GB at ₦150 per GB, and any usage above 500 GB at ₦100 per GB. After how many whole months will the monthly charge first exceed ₦80,000? Give your answer as the smallest integer month number.

A. 14

Correct B. 13

C. 15

D. 12

Correct Answer: B

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Question 23 View Details

The total time to complete a data‑processing cycle is 48 minutes. The stages are: Collection (C), Validation (V), Processing (P), Storage (S) and Presentation (R). Collection takes 20\% of the total time and Validation takes 15\% of the total time. Processing takes twice as long as Storage, and Presentation takes 5 minutes longer than Storage. How many minutes are spent on Processing?

A. 14.0

B. 13.5

C. 12.8

Correct D. 13.1

Correct Answer: D

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Question 24 View Details

A spreadsheet records monthly sales (in units) of three products for six months as follows:\n\nMonth 1: A 1200, B 800, C 500\nMonth 2: A 1300, B 850, C 550\nMonth 3: A 1250, B 900, C 600\nMonth 4: A 1400, B 950, C 650\nMonth 5: A 1500, B 1000, C 700\nMonth 6: A 1600, B 1100, C 800\n\nFor each month compute the total sales, then the month‑to‑month growth rate (percentage). Using the proportion of each month's total sales to the overall total sales as a weight, find the weighted average growth rate (to one decimal place). Also state which month contributed the most to the overall growth (i.e., has the highest weighted contribution).

A. 6.4%, 4

B. 5.9%, 5

Correct C. 6.1%, 6

D. 6.1%, 5

Correct Answer: C

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Question 25 View Details

Consider a relation R(A,B,C,D,E) with functional dependencies: A\to B, BC\to D, D\to E.\n\n(a) List all candidate keys of R.\n(b) State the highest normal form that R satisfies.\n(c) Give a lossless‑join, dependency‑preserving decomposition of R into BCNF relations.

A. 1NF; R1(A,B,C), R2(C,D), R3(D,E)

Correct B. 1NF; R1(A,B), R2(A,C,D), R3(D,E)

C. BCNF; R1(A,B), R2(A,C,D), R3(D,E)

D. 2NF; R1(A,B), R2(B,C,D), R3(D,E)

Correct Answer: B

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