Practice neco computer_studies 2018 Past Questions

Question 1 View Details

In a hybrid network, each department uses a star topology with 6 computers. The cable from each computer to the department switch is $5$ metres long. The four department switches are connected in a linear bus backbone; each bus segment between adjacent switches is $20$ metres long. Determine the total length of cable required for the entire network, in metres.

Correct A. 180

B. 200

C. 160

D. 190

Correct Answer: A

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Question 2 View Details

Consider the following Python program:\n\n```python\nfor i in range(1, n+1):\n for j in range(1, i+1):\n print("*", end="")\n if i % 2 == 0:\n print("@", end="")\nprint("#" * n)\n```\nThe program prints a sequence of characters consisting of asterisks (\*), at‑signs (\@) and hash symbols (\#). If the total number of characters printed by the program is $70$, determine the value of $n$.

A. 8

B. 12

C. 14

Correct D. 10

Correct Answer: D

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Question 3 View Details

Place the following milestones in chronological order, from earliest to latest: (A) Development of the first transistor, (B) Invention of the ENIAC computer, (C) Release of the IBM PC.

Correct A. B, A, C

B. B, C, A

C. C, A, B

D. A, B, C

Correct Answer: A

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Question 4 View Details

Given the following CSS rules:\n\n1) \#menu .item { color: red; }\n2) .nav .item { color: blue; }\n3) div.item { color: green; }\n\nAnd the HTML fragment:\n\n```html\n<div id="menu" class="nav"><p class="item">Link</p></div>\n```\nWhich colour will be applied to the text inside the \<p\> element?

A. green

B. blue

C. black

Correct D. red

Correct Answer: D

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Question 5 View Details

A company implements a RAID 5 array consisting of 5 disks, each with a capacity of $2$ TB. Files to be stored are exactly $500$ GB in size.\n\n(a) What is the maximum number of whole $500$ GB files that can be stored on the array?\n(b) What percentage of the total raw disk capacity is used for actual data (excluding parity)? Express the percentage as a whole number.

A. 16 files, 75%

B. 15 files, 75%

C. 15 files, 80%

Correct D. 16 files, 80%

Correct Answer: D

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Question 6 View Details

Consider the following pseudocode:\n\ncount = 0\nfor i = 1 to n\n for j = i to n\n if (j mod i = 0)\n count = count + 1\n\nWhat is the value of $count$ after the loops finish when $n = 12$?

Correct A. 35

B. 28

C. 30

D. 36

Correct Answer: A

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Question 7 View Details

An organization evaluates risk using the formula $R = T \times V \times I$, where T (threat), V (vulnerability) and I (impact) are rated on a scale of 1 to 5. A risk is classified as \"high\" if $R \ge 60$, \"medium\" if $30 \le R < 60$, and \"low\" if $R < 30$. The organization has identified three threats with threat ratings T₁=4, T₂=3 and T₃=5. For each threat, the possible vulnerability ratings are 2 or 4, and the possible impact ratings are 1, 3 or 5. How many distinct threat‑vulnerability‑impact combinations result in a \"high\" risk?

A. 5

B. 3

Correct C. 4

D. 6

Correct Answer: C

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Question 8 View Details

An organization has been allocated the IPv4 address block $192.168.64.0/20$. It needs to create subnets each capable of supporting at least 500 usable host addresses, and each subnet must consist of a contiguous block of addresses. Determine the maximum number of such subnets that can be created and give the required subnet mask in dotted‑decimal notation.

A. 8 subnets, mask 255.255.255.0 (\/24)

Correct B. 8 subnets, mask 255.255.254.0 (/23)

C. 6 subnets, mask 255.255.252.0 (\/22)

D. 7 subnets, mask 255.255.254.0 (\/23)

Correct Answer: B

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Question 9 View Details

A password policy requires passwords to be exactly 8 characters long, each character chosen from the 94 printable ASCII characters. Thus the total password space contains $94^{8}$ possible passwords. An attacker can compute hashes at a rate of $2^{30}$ hashes per second using a GPU. Estimate the expected time, in years, to exhaust the entire password space. Based on your result, comment on whether such a brute‑force attack is feasible within one year.

A. Approximately 0.018 years (about 6.6 days); therefore the attack is feasible within a year.

B. Approximately 1.8 years (about 660 days); therefore the attack is not feasible within a year.

C. Approximately 18 years (about 6570 days); therefore the attack is not feasible within a year.

Correct D. Approximately 0.18 years (about 66 days); therefore the attack is feasible within a year.

Correct Answer: D

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Question 10 View Details

The following recursive function is defined:\n\nF(n):\n if n \le 1 return 1\n else return F(n‑1) + 2·F(n‑2)\n\nDerive a closed‑form expression for $F(n)$ and compute $F(10)$.

Correct A. 683

B. 685

C. 671

D. 699

Correct Answer: A

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Question 11 View Details

A company has been allocated the IPv4 address block 172.16.0.0/16. Each subnet must support at least $500$ hosts. Determine the subnet mask that satisfies this requirement and state the maximum number of subnets that can be created from the given address block.

Correct A. Subnet mask 255.255.254.0; maximum subnets 128

B. Subnet mask 255.255.248.0; maximum subnets 32

C. Subnet mask 255.255.255.0; maximum subnets 256

D. Subnet mask 255.255.252.0; maximum subnets 64

Correct Answer: A

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Question 12 View Details

The Intel 4004 microprocessor was released in $1971$. Three years later, the Altair 8800, considered the first commercially successful personal computer, was introduced. In what year was the Altair 8800 introduced?

A. 1976

B. 1972

Correct C. 1974

D. 1975

Correct Answer: C

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Question 13 View Details

A sorting algorithm runs in time proportional to the square of the number of items processed, i.e., $T = k n^{2}$. For a data set of 500 items the algorithm takes 125 seconds. Assuming the same constant $k$ applies, how many seconds will the algorithm take for a data set of 800 items?

A. 160

Correct B. 320

C. 400

D. 200

Correct Answer: B

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Question 14 View Details

A symmetric‑key encryption algorithm uses a 128‑bit key. An attacker can test $2^{30}$ keys per second. Estimate how many years it would take to exhaust the entire key space by brute‑force, and state whether this time is less than, equal to, or greater than one year.

A. Approximately 9.4×10^{21} years (less than one year)

Correct B. Approximately 9.4×10^{21} years (greater than one year)

C. Approximately 5.0×10^{22} years (greater than one year)

D. Approximately 1.2×10^{9} years (greater than one year)

Correct Answer: B

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Question 15 View Details

Consider the following Python code intended to compute the sum of all natural numbers less than N that are multiples of 3 or 5: ```python total = 0 for i in range(1, N): if i % 3 == 0 and i % 5 == 0: total += i print(total) ``` If the variable `N` is set to 20, (a) identify the logical error in the code, (b) rewrite the condition correctly, and (c) give the correct output produced by the corrected program.

A. 73

Correct B. 78

C. 80

D. 75

Correct Answer: B

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Question 16 View Details

Consider a relation R(A,B,C,D,E) with functional dependencies $ \{A \rightarrow B, A \rightarrow C, BC \rightarrow D, D \rightarrow E\} $. (a) State the highest normal form that R satisfies. (b) Decompose R into BCNF using the standard decomposition algorithm and give the number of resulting relations.

A. BCNF; 2 relations

B. 1NF; 3 relations

Correct C. 2NF; 4 relations

D. 3NF; 5 relations

Correct Answer: C

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Question 17 View Details

Relation S(A,B,C,D) has functional dependencies $ \{A \rightarrow B, B \rightarrow C, C \rightarrow D, A \rightarrow D\} $. (a) Find a minimal cover of the set. (b) Using the minimal cover, produce a lossless‑join, dependency‑preserving decomposition of S into 3NF and state how many relations are in the decomposition.

Correct A. 3

B. 5

C. 4

D. 2

Correct Answer: A

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Question 18 View Details

An information file contains four symbols A, B, C, D with frequencies 45, 13, 12 and 30 respectively (total 100). Construct the Huffman code for these symbols, then compute the average code length in bits per symbol.

A. 2.0

Correct B. 1.8

C. 2.2

D. 1.5

Correct Answer: B

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Question 19 View Details

In a spreadsheet, cells A2:A6 contain sales amounts 1200, 2500, 4800, 7500 and 11000 respectively. The commission rates are: up to 2000 → 5 %; 2001-5000 → 7 %; above 5000 → 10 %. (a) Write a formula for cell B2 that can be copied down to compute the commission for each sale using nested IF. (b) Calculate the total commission payable for the five sales.

A. 2500

Correct B. 2421

C. 2361

D. 2445

Correct Answer: B

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Question 20 View Details

A software vendor sells licenses with the following tiered pricing: first 10 licenses at $150 each, the next 40 licenses at $120 each, and any additional licenses at $100 each. How much will a company pay for 73 licenses?

A. 8370

B. 9000

Correct C. 8600

D. 7800

Correct Answer: C

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Question 21 View Details

The scores are grouped as follows: 0-39: 15 students; 40-59: 30 students; 60-79: ? students; 80-100: 45 students. The overall mean score is $68$. Find the number of students who scored between 60 and 79 inclusive, and then determine what percentage of the class scored 60 or above (rounded to the nearest whole percent).

A. 200 students; 85%

Correct B. 195 students; 84%

C. 190 students; 83%

D. 180 students; 80%

Correct Answer: B

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Question 22 View Details

An organisation is allocated the network $192.168.48.0/20$. It needs subnets that can each support at least $500$ usable host addresses. Determine the new subnet mask in dotted‑decimal notation, the total number of such subnets that can be created, and give the network address of the first subnet.

A. Mask 255.255.255.0; 16 subnets; first subnet 192.168.48.0/24

Correct B. Mask 255.255.254.0; 8 subnets; first subnet 192.168.48.0/23

C. Mask 255.255.254.0; 6 subnets; first subnet 192.168.48.0/23

D. Mask 255.255.252.0; 4 subnets; first subnet 192.168.48.0/22

Correct Answer: B

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Question 23 View Details

Consider the following Python function intended to compute the sum of the squares of all even numbers less than $n$ that are also multiples of 3: ```python def sum_even_mult3(n): total = 0 for i in range(n): if i % 2 == 0 and i % 3 == 0: total += i ** 2 return total ``` The function contains a logical error. After correcting the error, what value does the function return when called with $n = 30$?

Correct A. 1080

B. 900

C. 720

D. 1260

Correct Answer: A

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Question 24 View Details

A desktop computer has the following components with their typical power consumptions: CPU 95 W, GPU 150 W, HDD 10 W, SSD 5 W, two RAM sticks 4 W each, motherboard 30 W, cooling fan 5 W. The power‑supply unit (PSU) operates at an efficiency of 85 %. What is the minimum PSU rating (in watts) that should be selected, rounding up to the nearest 50 W increment?

Correct A. 400 W

B. 350 W

C. 450 W

D. 375 W

Correct Answer: A

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Question 25 View Details

Who is widely recognised as the "father of the computer" for his design of the Analytical Engine in the 19th century?

A. Ada Lovelace

B. John von Neumann

Correct C. Charles Babbage

D. Alan Turing

Correct Answer: C

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