Practice neco computer_studies 2024 Past Questions

Question 1 View Details

An accountant uses a spreadsheet to compute weekly pay. Regular hours are paid at the rate in column B, overtime (hours beyond$40$) at 1.5\times that rate. Tax is applied progressively: 10\% on the first $\text{₦}20\,000$, 15\% on the next $\text{₦}30\,000$ and 20\% on any remaining amount. For employee John, the spreadsheet shows $48$ hours worked and a rate of $\text{₦}500$ per hour. (a) Calculate John's net pay after tax. (b) A summary report lists the net pay of 150 employees, one per line. Each line can contain at most 70 characters and a page can hold 40 lines. Assuming every line uses the maximum possible characters, how many pages are required for the report?

A. 5

B. 6

Correct C. 4

D. 3

Correct Answer: C

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Question 2 View Details

The following Python function processes a list of integers:\n\n```python\ndef process(nums):\n # remove duplicates\n uniq = list(set(nums))\n # sort in descending order\n uniq.sort(reverse=True)\n # sum numbers that are multiples of 3 but not of 5\n total = sum(x for x in uniq if x % 3 == 0 and x % 5 != 0)\n return total\n```\n\nIf the list passed to the function is $[12, 7, 15, 9, 12, 20, 33, 45, 9, 27, 30, 33]$, what integer does the function return?

Correct A. 81

B. 135

C. 171

D. 198

Correct Answer: A

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Question 3 View Details

A desktop computer uses the following components:\n- CPU: 95\,W\n- GPU: 150\,W\n- Two hard‑disk drives, each 10\,W\n- One solid‑state drive, 5\,W\n- Three case fans, each 3\,W\n\nThe power‑supply unit (PSU) is rated at 500\,W with an efficiency of 85\% at full load. The designer wants the total load to stay below 80\% of the PSU's usable power. How many additional watts can be allocated to peripheral devices without exceeding this limit?

A. 55

Correct B. 61

C. 73

D. 68

Correct Answer: B

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Question 4 View Details

A company's password policy requires passwords of length$8$ that contain at least one uppercase letter, one lowercase letter, one digit and one special character (chosen from the set \{!, @, #, $, %, ^, &, *, ?, \}\) of 10 symbols). Characters may be repeated.\n\n(a) Using inclusion-exclusion, determine the total number of possible passwords that satisfy the policy.\n(b) If an attacker can test 10\,000 passwords per second, how many years (to the nearest whole year) would it take to try 10\% of the entire password space? (Assume 1\,year = 365\,days.)

A. 110

Correct B. 98

C. 95

D. 102

Correct Answer: B

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Question 5 View Details

A small office network must connect eight computers.\n- In a star topology each computer is linked directly to a central hub. The cable lengths from the hub to the computers are: 5\,m, 7\,m, 6\,m, 8\,m, 5\,m, 9\,m, 4\,m and 6\,m.\n- In a bus topology the computers are placed linearly with an equal spacing of 3\,m between adjacent computers. The bus cable runs the full length of the line, and each computer has a 1\,m drop cable to the bus.\nCalculate the total cable length required for each topology and state which topology uses less cable.

A. Star topology, 50 m

B. Star topology, 29 m

Correct C. Bus topology, 29 m

D. Bus topology, 31 m

Correct Answer: C

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Question 6 View Details

Consider a relation R(A,B,C,D,E) with functional dependencies: $A\rightarrow B$, $BC\rightarrow D$, $D\rightarrow E$. Determine the highest normal form of R. Then decompose R into Boyce‑Codd Normal Form (BCNF) and state how many relations result from the decomposition.

A. 2NF; 2

Correct B. 1NF; 3

C. BCNF; 1

D. 3NF; 4

Correct Answer: B

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Question 7 View Details

A web page has a viewport width of 1200\,px. A container div with id "outer" is set to width 80\% of the viewport. Inside it, a div with class "inner" has width 50\% of its parent, padding of 10\,px on each side, a border of 2\,px, and a horizontal margin equal to 5\% of the outer div's width. What is the final rendered width of the inner div in pixels? Additionally, given the following CSS rules: p { color: red; } .article p { color: blue; } #main .article p { color: green; } and the HTML structure <div id="main"><div class="article"><p>Sample</p></div></div>, what color will the paragraph text appear?

A. green, 580px

Correct B. green, 600px

C. red, 600px

D. blue, 560px

Correct Answer: B

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Question 8 View Details

A computer system includes the following components with their power consumptions: CPU\,65\,W, GPU\,120\,W, HDD\,10\,W, SSD\,5\,W, motherboard\,30\,W, and two case fans each consuming 5\,W. Calculate the total power required and, adding a 20\% safety margin, recommend the minimum standard PSU rating (in whole watts) that should be selected.

A. 280

B. 350

Correct C. 300

D. 320

Correct Answer: C

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Question 9 View Details

The following pseudo‑code implements a bubble sort with an early‑exit flag: repeat swapped = false for i = 1 to n-1 if A[i] > A[i+1] then swap A[i], A[i+1] swapped = true until not swapped If the array is already sorted and n = 6, how many comparisons are performed? Also, what is the maximum number of comparisons for n = 6 in the worst case? State the results and the algorithm's time‑complexity class.

A. 5 comparisons (best case), 12 comparisons (worst case), O(n^2)

Correct B. 5 comparisons (best case), 15 comparisons (worst case), O(n^2)

C. 6 comparisons (best case), 15 comparisons (worst case), O(n^2)

D. 5 comparisons (best case), 15 comparisons (worst case), O(n log n)

Correct Answer: B

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Question 10 View Details

An organization evaluates risk for three assets: data valued at $\text{₦}100{,}000$, hardware valued at $\text{₦}50{,}000$, and reputation valued at $\text{₦}200{,}000$. For each asset a threat is identified with a likelihood (L) and a vulnerability factor (V). The impact is calculated as Asset\,value \times V, and risk as L \times Impact. The data threat has L = 0.2, V = 0.5; the hardware threat has L = 0.3, V = 0.4; the reputation threat has L = 0.1, V = 0.9. Which asset has the highest risk and what is that risk value (in naira)?

A. data, 10000

Correct B. reputation, 18000

C. hardware, 6000

D. reputation, 10000

Correct Answer: B

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Question 11 View Details

A computer system uses the following components: CPU 95 W, GPU 150 W, hard‑disk 10 W, solid‑state drive 5 W, four fans each consuming 3 W, and a motherboard that uses 30 W. The power‑supply unit (PSU) is rated at 500 W. Its efficiency varies linearly with load: at $20\%$ load the efficiency is 92\%, and at $100\%$ load the efficiency is 78\%. Assuming the system draws a total load of 380 W, determine (a) the efficiency of the PSU at this load, (b) the total power that must be drawn from the mains, and (c) the amount of power dissipated as heat in the PSU. Give your answers to the nearest watt.

A. Efficiency ≈ 78 %; Input power ≈ 487 W; Heat dissipated ≈ 107 W

Correct B. Efficiency ≈ 82 %; Input power ≈ 463 W; Heat dissipated ≈ 83 W

C. Efficiency ≈ 80 %; Input power ≈ 475 W; Heat dissipated ≈ 95 W

D. Efficiency ≈ 84 %; Input power ≈ 452 W; Heat dissipated ≈ 72 W

Correct Answer: B

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Question 12 View Details

A company's password policy requires passwords of length eight characters. The allowed characters are 26 uppercase letters, 26 lowercase letters, 10 digits and 10 special symbols. A valid password must contain at least one uppercase letter, at least one digit and at least one special symbol (lower‑case letters are optional). Determine (a) the total number of possible passwords that satisfy the policy, and (b) the probability that a randomly generated eight‑character string (using all 72 allowed characters with equal likelihood) meets the policy. Express your answer for (a) as an exact integer and for (b) as a reduced fraction.

Correct A. Valid = 72^{8} - (46^{8}+2·62^{8}) + (2·36^{8}+52^{8}) - 26^{8}; Probability = Valid / 72^{8}

B. Valid = 72^{8} - (46^{8}+2·62^{8}) - 26^{8}; Probability = Valid \/ 72^{8}

C. Valid = 72^{8} - (46^{8}+3·62^{8}) + (2·36^{8}+52^{8}) - 26^{8}; Probability = Valid \/ 72^{8}

D. Valid = 72^{8} - (46^{8}+2·62^{8}) + (2·36^{8}+52^{8}) - 26^{8}; Probability = Valid \/ 70^{8}

Correct Answer: A

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Question 13 View Details

A company wants to allocate a private IPv4 address space to five departments using a single Class C network (256 addresses). Each department must receive an equal number of usable host addresses, and each subnet must be a power‑of‑two size (including network and broadcast addresses). What subnet mask should be assigned to each department, and how many usable host addresses does each subnet provide?

A. Subnet mask \/26 (255.255.255.192); 62 usable host addresses per department

B. Subnet mask \/29 (255.255.255.248); 6 usable host addresses per department

C. Subnet mask \/28 (255.255.255.240); 14 usable host addresses per department

Correct D. Subnet mask /27 (255.255.255.224); 30 usable host addresses per department

Correct Answer: D

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Question 14 View Details

Who is widely recognised as the father of the stored‑program computer architecture?

A. Charles Babbage

B. Alan Turing

Correct C. John von Neumann

D. John Backus

Correct Answer: C

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Question 15 View Details

Consider a relation R(A,B,C,D) containing 1,000 tuples. The functional dependencies are $A \rightarrow B$, $B \rightarrow C$, and $C \rightarrow D$.\n\n(a) Identify the candidate key(s) of R and state the highest normal form that R satisfies.\n(b) Decompose R into a set of relations that are in Boyce‑Codd Normal Form (BCNF) while preserving all functional dependencies. List the resulting relations.\n(c) Assuming that in the original relation each distinct value of A appears the same number of times, that A uniquely determines B, B uniquely determines C and C uniquely determines D, and that there are exactly 100 distinct A values, compute the total number of tuples stored across all the BCNF relations obtained in part (b).

A. Total tuples after BCNF decomposition = 600

B. Total tuples after BCNF decomposition = 300

Correct C. Total tuples after BCNF decomposition = 400

D. Total tuples after BCNF decomposition = 500

Correct Answer: C

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Question 16 View Details

A file of 2,560,000 bits is to be compressed using two techniques: Technique A reduces the file size by $30\%$ of the original size, while Technique B reduces the current size by $20\%$. Each technique can be used only once, and the order of application can be chosen. Which order yields the smallest final file size, and what is that size in bits?

A. Apply Technique A first, then Technique B; final size = 1,536,000 bits

Correct B. Apply Technique B first, then Technique A; final size = 1,280,000 bits

C. Apply Technique A first, then Technique B; final size = 1,280,000 bits

D. Apply Technique B first, then Technique A; final size = 1,433,600 bits

Correct Answer: B

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Question 17 View Details

An 8‑bit data block is transmitted with an even parity bit added, making a total of 9 bits. If the probability that any single bit (including the parity bit) flips during transmission is $p = 0.001$, what is the probability that the receiver detects an error?

Correct A. 0.008928

B. 0.0095

C. 0.0080

D. 0.0102

Correct Answer: A

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Question 18 View Details

Consider the following pseudocode where $n$ is a positive integer:\n\n``\ncount = 0\nfor i = 1 to n\n for j = i to n\n if (i + j) mod 3 = 0\n count = count + 1\n```\n\nFor $n = 12$, what is the value of $count$? Also give a closed‑form expression for $count$ as a function of $n$.

A. 28; count = a(a+1)\/2 + b·c + 1 where a,b,c are the numbers of residues 0,1,2 modulo 3 respectively (see solution for piecewise formula).

Correct B. 26; count = a(a+1)/2 + b·c where a,b,c are the numbers of residues 0,1,2 modulo 3 respectively (see solution for piecewise formula).

C. 30; count = a·b + c·(c+1)\/2 where a,b,c are the numbers of residues 0,1,2 modulo 3 respectively (see solution for piecewise formula).

D. 24; count = a(a-1)\/2 + b·c where a,b,c are the numbers of residues 0,1,2 modulo 3 respectively (see solution for piecewise formula).

Correct Answer: B

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Question 19 View Details

An organization requires at least 30 sub‑networks, each supporting up to 200 hosts. Using the class‑B address block $172.16.0.0$ (default mask $255.255.0.0$), determine the subnet mask (in dotted‑decimal notation) that satisfies the requirements with the least amount of wasted host addresses, and state the number of usable host addresses per subnet.

Correct A. 255.255.255.0 and 254 usable host addresses per subnet

B. 255.255.255.128 and 126 usable host addresses per subnet

C. 255.255.254.0 and 510 usable host addresses per subnet

D. 255.255.252.0 and 1022 usable host addresses per subnet

Correct Answer: A

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Question 20 View Details

A company's quarterly sales (in thousand Naira) for 2023 are: Q1 - 120, Q2 - 150, Q3 - 135, Q4 - 165.\n\n(a) What is the overall percentage increase in sales from Q1 to Q4?\n(b) Assuming the sales grew at a constant quarterly rate $r$ (geometric growth), find $r$ expressed as a percentage, rounded to two decimal places.

A. 45.0% overall increase; 12.50% quarterly growth rate

B. 37.5% overall increase; 10.00% quarterly growth rate

Correct C. 37.5% overall increase; 11.20% quarterly growth rate

D. 40.0% overall increase; 11.20% quarterly growth rate

Correct Answer: C

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Question 21 View Details

A class of 80 students took a test. Their scores are grouped as follows: 40‑49: 12 students, 50‑59: 18 students, 60‑69: ___ students, 70‑79: 14 students, 80‑89: 6 students. The overall mean score is $63$. Find the missing frequency for the 60‑69 group and state the modal class.

Correct A. 30, 60‑69

B. 35, 60‑69

C. 25, 60‑69

D. 30, 70‑79

Correct Answer: A

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Question 22 View Details

Consider the following pseudo‑code: \n\n``\nread n\ncount = 0\nfor i = 1 to n\n for j = 1 to i\n if (j mod 3 = 0) then\n count = count + 1\n end if\n next j\nnext i\nprint count\n``\n\nIf the input value is $n = 12$, what number is printed?

A. 20

B. 18

C. 24

Correct D. 22

Correct Answer: D

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Question 23 View Details

Which computer hardware component is primarily responsible for converting digital audio data into analog signals that can drive a pair of loudspeakers?

A. network card

Correct B. sound card

C. graphics card

D. motherboard

Correct Answer: B

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Question 24 View Details

A web page contains the following CSS rules: \n\n```css\np {color: blue;}\n.highlight {color: red;}\n#intro {color: green;}\ndiv.container p {color: orange;}\n\n.container {width: 200px; padding: 10px; border: 5px solid black; margin: 15px;}\n```\n\nThe HTML fragment is: \n\n```html\n<div class="container">\n <p id="intro" class="highlight">Sample text</p>\n</div>\n```\n\n(a) What is the final text colour of the paragraph as rendered by the browser?\n(b) What is the total horizontal space occupied by the outer edge of the <div class="container"> element (including margin, border, padding and content)?

A. blue, 230

B. red, 260

C. green, 250

Correct D. green, 260

Correct Answer: D

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Question 25 View Details

In a spreadsheet, Sheet1 contains the following data (columns A and B):\n\n| A (Item) | B (Qty) | C (Unit Price) |\n|----------|--------|----------------|\n| A | 5 | 12 |\n| B | 3 | 20 |\n| C | 7 | 8 |\n\nSheet2 has a discount table based on the subtotal (column D):\n\n| D (Subtotal) | E (Discount %) |\n|---------------|----------------|\n| ≥ 200 | 15 |\n| ≥ 100 | 10 |\n| < 100 | 5 |\n\nWrite the formula that would compute the final amount payable (subtotal minus discount) in a single cell on Sheet1, and state the numeric final amount for the data given above.

Correct A. 158.4

B. 149.6

C. 108.0

D. 167.2

Correct Answer: A

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