Practice neco computer_studies 2019 Past Questions

Question 1 View Details

Consider the following HTML and CSS: HTML: <div id="main"> <p class="intro" style="color: yellow;">Sample text</p> </div> CSS: #main p.intro { color: blue; } .intro { color: green !important; } p { color: red; } What will be the computed text colour of the paragraph when rendered in a browser?

Correct A. green

B. yellow

C. blue

D. red

Correct Answer: A

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Question 2 View Details

Given two 8‑bit two's complement binary numbers A = $01101101_2$ and B = $10110110_2$, add them using binary addition. State the decimal value of the sum and indicate whether an overflow occurs.

A. -35, No overflow

Correct B. 35, No overflow

C. 35, Yes overflow

D. 109, No overflow

Correct Answer: B

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Question 3 View Details

Relation R(A,B,C,D,E) has the functional dependencies: A→B, B→C, AC→D, D→E. a) List all candidate keys of R. b) State the highest normal form (up to BCNF) that R satisfies. c) Provide a lossless‑decomposition of R into relations that are in BCNF.

A. a) AD; b) 2NF; c) {R1(A,B), R2(B,C), R3(D,E)}

Correct B. a) AC; b) 1NF; c) {R1(A,B), R3(D,E), R4(A,C,D)}

C. a) A; b) BCNF; c) {R1(A,B), R2(B,C), R3(C,D), R4(D,E)}

D. a) AB; b) 3NF; c) {R1(A,B,C), R2(C,D), R3(D,E)}

Correct Answer: B

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Question 4 View Details

Which type of CPU cache is typically the fastest and located closest to the processor core?

A. L2 cache

B. TLB

C. L3 cache

Correct D. L1 cache

Correct Answer: D

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Question 5 View Details

A computer system has the following components: - CPU: 65 W at 12 V - GPU: 150 W at 12 V - Hard disk drive: 10 W at 5 V - Solid‑state drive: 5 W at 5 V - Three case fans: each 2 W at 12 V The power‑supply unit (PSU) operates at an efficiency of 85 %. a) Calculate the total power that must be supplied by the PSU. b) Is a 500 W PSU adequate for this system? Answer "Yes" or "No".

Correct A. a) 278 W; b) Yes

B. a) 300 W; b) Yes

C. a) 278 W; b) No

D. a) 236 W; b) Yes

Correct Answer: A

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Question 6 View Details

Consider the HTML element: <p id=\"intro\" class=\"highlight\" style=\"color: blue;\">Sample text</p>. The external stylesheet contains these rules in the order shown:\n1. p { color: red; }\n2. .highlight { color: green; }\n3. #intro { color: #FF6600; }\n\n(a) What colour will the paragraph be rendered in? Express the colour as a hexadecimal code.\nLater the developer adds another rule at the end of the stylesheet:\n4. body p.highlight { color: #123456; }\nand removes the inline style attribute from the element.\n\n(b) After these changes, what colour will the paragraph be rendered in? Express the colour as a hexadecimal code.

Correct A. #0000FF, #FF6600

B. #00FF00, #FF6600

C. #0000FF, #123456

D. #FF0000, #123456

Correct Answer: A

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Question 7 View Details

The following Python code is executed:\n\ncount = 0\nfor i in range(1, 5):\n for j in range(i, 6):\n if (i * j) % 3 == 0:\n count += 1\ntotal = count * 2\nprint(total)\n\nWhat integer value is printed by the program?

A. 14

B. 8

C. 12

Correct D. 10

Correct Answer: D

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Question 8 View Details

A processor has 4 cores and each core supports hyper‑threading, allowing up to 2 threads per core. What is the maximum number of threads that can run concurrently on this CPU?

A. 16

Correct B. 8

C. 12

D. 4

Correct Answer: B

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Question 9 View Details

An organisation has been allocated the class B network 172.16.0.0/16. It needs subnets that can each accommodate up to 200 usable host addresses. Determine the subnet mask that should be used (in CIDR notation) and the total number of such subnets that can be created from the original network.

A. /24, 128

Correct B. /24, 256

C. /23, 128

D. /25, 512

Correct Answer: B

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Question 10 View Details

A block‑level element has the following CSS box model values: width: 300px; padding: 20px on the left and right; border: 5px on the left and right; margin: 15px on the left and right. The containing block is 800px wide. How many pixels of horizontal space remain on each side of the element (i.e., the space between the outer edge of the element and the container edge)?

A. 225

B. 230

Correct C. 210

D. 215

Correct Answer: C

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Question 11 View Details

A software project follows the Waterfall model with five phases whose original time allocations are: Requirements 20%, Design 25%, Implementation 30%, Testing 15% and Maintenance 10% of the total project time. The total planned time is 1200 hours. Due to a design change, the Implementation phase actually requires 20% more time than its original allocation, and the Testing phase is reduced proportionally so that the overall project time remains 1200 hours. What is the new duration (in hours) of the Testing phase?

A. 96

B. 180

Correct C. 108

D. 120

Correct Answer: C

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Question 12 View Details

Consider the following Python code: ```python numbers = [12, 7, 5, 20, 15] result = 0 for i in range(len(numbers)): if numbers[i] % 3 == 0: numbers[i] = numbers[i] // 3 else: numbers[i] = numbers[i] * 2 if i % 2 == 0: result += numbers[i] else: result -= numbers[i] ``` What is the final value of `result` after the loop finishes?

A. -30

Correct B. -35

C. -45

D. -40

Correct Answer: B

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Question 13 View Details

In which year was the ENIAC, the first general‑purpose electronic computer, officially commissioned?

A. 1945

Correct B. 1946

C. 1947

D. 1950

Correct Answer: B

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Question 14 View Details

A relation R(A,B,C,D,E) has the following functional dependencies: $A \rightarrow B$, $BC \rightarrow D$, $D \rightarrow E$, $E \rightarrow A$.\n\n(a) List all candidate keys of R.\n(b) State the highest normal form (up to BCNF) that R satisfies.

Correct A. Candidate keys: AC and BC; Highest normal form: 1NF

B. Candidate keys: AC and AD; Highest normal form: 3NF

C. Candidate keys: AB and BC; Highest normal form: BCNF

D. Candidate keys: AB and AD; Highest normal form: 2NF

Correct Answer: A

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Question 15 View Details

An organization assesses three threats with the following likelihood (Low=1, Medium=2, High=3) and impact (Low=1, Medium=2, High=3) values: Threat A - likelihood 3, impact 2; Threat B - likelihood 2, impact 3; Threat C - likelihood 1, impact 3. The risk rating for a threat is calculated as $\text{likelihood} \times \text{impact}$. The organization can implement at most two controls; each control reduces the likelihood of a chosen threat by one level (but not below Low). Which two threats should be selected for mitigation to achieve the lowest possible total risk rating after mitigation?

A. Threats A and B (suboptimal)

B. Threats B and C

Correct C. Threats A and B

D. Threats A and C

Correct Answer: C

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Question 16 View Details

Consider a relation R(A,B,C,D) with functional dependencies: $ A \rightarrow B $, $ B \rightarrow C $, and $ AC \rightarrow D $. (a) List all candidate keys of R. (b) State the highest normal form that R satisfies. (c) If R is not in Boyce‑Codd Normal Form, decompose it into BCNF relations and give the number of resulting relations.

A. AC; 1NF; 4

Correct B. A; 2NF; 3

C. AB; 3NF; 2

D. AD; BCNF; 5

Correct Answer: B

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Question 17 View Details

An Excel worksheet records quarterly sales for ten products. For each product, the sales for Q1 to Q4 are entered in columns B to E of rows 2 to 11. Column F should show the total annual sales for that product, and row 12 should show the total sales for each quarter across all products. Provide: 1. The formula to place in cell F2 that can be copied down to compute each product's total. 2. The formula to place in cell B12 that can be copied across to compute each quarter's total. 3. The formula to place in cell G2 that gives the percentage contribution of that product's total to the overall total (which will be in cell G12), and can be copied down.

Correct A. =SUM(B2:E2); =SUM(B$2:B$11); =F2/\$F\$12*100

B. =SUM(B2:E2); =SUM(B$2:B$11); =F2*\$F\$12*100

C. =SUM(B2:D2); =SUM(B$2:B$11); =F2\/\$F\$12/100

D. =SUM(B2:E2); =SUM(B2:B11); =F2\/\$F\$12*100

Correct Answer: A

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Question 18 View Details

A data file of size 1024 bytes is to be transmitted using a block error‑detecting code that appends a 2‑byte CRC to each 256‑byte block. (a) How many total bytes are transmitted? (b) If the bit‑error rate of the channel is $10^{-5}$, compute the probability that a given transmitted block is received without any error. Give the answer to four decimal places.

A. 1024; 0.9796

B. 1032; 0.9800

C. 1028; 0.9796

Correct D. 1032; 0.9796

Correct Answer: D

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Question 19 View Details

A program implements insertion sort on an array of $n$ distinct integers and counts the number of key comparisons performed. For $n = 20$ the program reports 190 comparisons. Assuming the input is a random permutation, the expected number of comparisons for insertion sort is $\frac{n(n-1)}{4}$ and the variance is $\frac{n(n-1)(2n+5)}{72}$. (a) Compute the expected number of comparisons and the standard deviation for $n = 20$. (b) State whether the observed count of 190 comparisons lies within one standard deviation of the expected value.

A. Expected = 95; StdDev ≈ 14.00; Not within one standard deviation

B. Expected = 95; StdDev ≈ 15.42; Within one standard deviation

Correct C. Expected = 95; StdDev ≈ 15.42; Not within one standard deviation

D. Expected = 100; StdDev ≈ 15.42; Not within one standard deviation

Correct Answer: C

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Question 20 View Details

An organization has been allocated the IPv4 address block $192.168.64.0/20$. It needs subnets for three departments with the following host requirements: Admin - 50 hosts; Sales - 120 hosts; R&D - 200 hosts. Determine a subnetting scheme that satisfies each requirement while minimizing wasted addresses. For each department give: 1. Subnet address and prefix length (in / notation). 2. First usable host IP and last usable host IP. Also state the range and size of the remaining unallocated address space.

A. R&D: 192.168.64.0\/25, usable 192.168.64.1‑192.168.64.126; Sales: 192.168.64.128\/26, usable 192.168.64.129‑192.168.64.190; Admin: 192.168.64.192\/27, usable 192.168.64.193‑192.168.64.222; Remaining: 192.168.64.224‑192.168.79.255 (3584 addresses)

Correct B. R&D: 192.168.64.0/24, usable 192.168.64.1‑192.168.64.254; Sales: 192.168.65.0/25, usable 192.168.65.1‑192.168.65.126; Admin: 192.168.65.128/26, usable 192.168.65.129‑192.168.65.190; Remaining: 192.168.65.192‑192.168.79.255 (3648 addresses)

C. R&D: 192.168.64.0\/23, usable 192.168.64.1‑192.168.65.254; Sales: 192.168.66.0\/25, usable 192.168.66.1‑192.168.66.126; Admin: 192.168.66.128\/26, usable 192.168.66.129‑192.168.66.190; Remaining: 192.168.66.192‑192.168.79.255 (3328 addresses)

D. R&D: 192.168.64.0\/24, usable 192.168.64.1‑192.168.64.254; Sales: 192.168.65.0\/25, usable 192.168.65.1‑192.168.65.126; Admin: 192.168.65.128\/26, usable 192.168.65.129‑192.168.65.190; Remaining: 192.168.65.191‑192.168.79.255 (3649 addresses)

Correct Answer: B

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Question 21 View Details

Consider the following Python code:\n\n```python\ncounter = 0\ndef foo(k):\n global counter\n for i in range(1, k+1):\n if i % 3 == 0:\n counter += i\n else:\n for j in range(i):\n if (j*i) % 4 == 0:\n counter += 1\n return counter\n\nx = foo(5)\ny = foo(3)\n```\n\nAfter executing the code, what is the value of the variable **y**?

A. 5

B. 14

Correct C. 16

D. 18

Correct Answer: C

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Question 22 View Details

In the history of computers, which microcomputer, introduced in 1975, is widely recognized as the first commercially successful personal computer?

A. TRS-80

B. Apple I

Correct C. Altair 8800

D. Commodore PET

Correct Answer: C

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Question 23 View Details

Given the following Python fragment:\n\n```python\ntext = "Data2023Science"\ndigits = [ch for ch in text if ch.isdigit()]\nletters = [ch for ch in text if ch.isalpha()]\nvowel_count = sum(1 for ch in letters if ch.lower() in 'aeiou')\nresult = vowel_count * len(digits)\n```\n\nWhat integer value is stored in **result** after execution?

Correct A. 20

B. 16

C. 24

D. 15

Correct Answer: A

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Question 24 View Details

A network contains 8 computers. In a fully‑connected mesh topology the number of individual links required is given by $ \frac{n(n-1)}{2} $ where $n$ is the number of computers. In a ring topology exactly $n$ links are needed. What is the difference between the number of links required for the mesh and the ring topologies for these 8 computers?

A. 16

B. 28

C. 8

Correct D. 20

Correct Answer: D

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Question 25 View Details

A software vendor sells licences as follows: the first 5 users are charged ₦20,000 each, and every additional user beyond the first five costs ₦12,000. If a school purchases licences for 23 users, what is the total amount payable in naira?

Correct A. 316000

B. 376000

C. 280000

D. 460000

Correct Answer: A

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