Practice city guilds model questions vol1 information_technology 2022 Past Questions

Question 1 View Details

A process is currently in the Ready queue. The CPU scheduler uses a preemptive round‑robin algorithm with a time quantum of $20\text{ ms}$. After $15\text{ ms}$ of CPU time, the process receives an I/O request that will take $30\text{ ms}$ to complete. List, in order, the states the process will pass through from the moment the I/O request is issued until it is ready to run again.

A. Running → Ready → Waiting (I/O)

B. Running → Waiting (I/O) → Blocked

C. Running → Waiting (I/O) → Ready → Running

Correct D. Running → Waiting (I/O) → Ready

Correct Answer: D

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Question 2 View Details

A presenter prepares a slide deck of $25$ slides. Each slide contains an image of average size $1.2\text{ MB}$ before compression. The presenter applies JPEG compression that reduces each image size by $40\%$ and then saves the whole presentation as a PDF, which adds a fixed overhead of $2\text{ MB}$. The classroom Wi‑Fi can deliver data at $5\text{ Mbps}$. The presenter wants the presentation to load in under $10\text{ s}$. Determine whether the compressed presentation will meet the loading‑time requirement.

A. No, it will take about 45 seconds, exceeding the 10‑second limit.

B. Yes, it will take about 8 seconds, meeting the 10‑second limit.

Correct C. No, it will take about 32 seconds, exceeding the 10‑second limit.

D. No, it will take about 9 seconds, meeting the 10‑second limit.

Correct Answer: C

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Question 3 View Details

A small office network is allocated the IPv4 block $192.168.48.0/22$. The administrator must create sub‑nets for three departments: Admin (needs at least 50 hosts), Sales (needs at least 120 hosts) and R\&D (needs at least 30 hosts). Sub‑nets must be contiguous and use the smallest possible masks. Determine the subnet mask and address range for each department, and state how many unused host addresses remain in the original $/22$ block after the allocation.

A. Sales: 192.168.48.0/25 (192.168.48.0 - 192.168.48.127); Admin: 192.168.48.128/26 (192.168.48.128 - 192.168.48.191); R&D: 192.168.48.224/27 (192.168.48.224 - 192.168.48.255); Unused hosts: 736

B. Sales: 192.168.48.0/25 (192.168.48.0 - 192.168.48.127); Admin: 192.168.48.128/26 (192.168.48.128 - 192.168.48.191); R&D: 192.168.48.192/27 (192.168.48.192 - 192.168.48.223); Unused hosts: 768

C. Sales: 192.168.48.0/26 (192.168.48.0 - 192.168.48.63); Admin: 192.168.48.64/25 (192.168.48.64 - 192.168.48.191); R&D: 192.168.48.192/27 (192.168.48.192 - 192.168.48.223); Unused hosts: 864

Correct D. Sales: 192.168.48.0/25 (192.168.48.0 - 192.168.48.127); Admin: 192.168.48.128/26 (192.168.48.128 - 192.168.48.191); R&D: 192.168.48.192/27 (192.168.48.192 - 192.168.48.223); Unused hosts: 800

Correct Answer: D

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Question 4 View Details

A company must back up a $12\text{ TB}$ data set. Two RAID options are considered:\n\n- RAID 5 using 6 disks of equal size.\n- RAID 6 using 8 disks of equal size.\n\nEach disk costs the same. The system must tolerate at least two simultaneous disk failures without data loss and provide at least $10\text{ TB}$ of usable storage. Determine the minimum disk capacity (in whole TB) required for each RAID level, and state which RAID level satisfies both requirements with the smallest total disk cost.

A. RAID 5 requires a minimum disk size of 2 TB, RAID 6 requires 3 TB. Only RAID 5 satisfies the two‑failure tolerance, using six 2 TB disks (total raw capacity 12 TB).

Correct B. Both RAID levels require a minimum disk size of 2 TB. Only RAID 6 satisfies the two‑failure tolerance, using eight 2 TB disks (total raw capacity 16 TB).

C. Both RAID levels require a minimum disk size of 3 TB. Only RAID 5 satisfies the two‑failure tolerance, using six 3 TB disks (total raw capacity 18 TB).

D. Both RAID levels require a minimum disk size of 2 TB. Only RAID 6 satisfies the two‑failure tolerance, using eight 2 TB disks (total raw capacity 16 TB), but the usable storage is only 8 TB.

Correct Answer: B

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Question 5 View Details

Convert the binary number $1011011_2$ to decimal, then state whether the resulting decimal number is divisible by 3.

A. Decimal value 93; divisible by 3

B. Decimal value 91; divisible by 3

Correct C. Decimal value 91; not divisible by 3

D. Decimal value 89; not divisible by 3

Correct Answer: C

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Question 6 View Details

A system has 3 frames. Using the LRU page‑replacement algorithm, the reference string is $1,2,3,4,1,2,5,1,2,3,4,5$. How many page faults occur?

A. 9

Correct B. 10

C. 11

D. 12

Correct Answer: B

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Question 7 View Details

Consider the function\n\n```\nint f(int n){\n int count = 0;\n for(int i = 1; i <= n; i++){\n for(int j = i; j <= n; j++){\n if((i + j) % 3 == 0){\n count++;\n }\n }\n }\n return count;\n}\n```\n\nWhat value does $f(12)$ return?

Correct A. 26

B. 28

C. 24

D. 30

Correct Answer: A

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Question 8 View Details

Given the relation $R(A,B,C,D,E)$ with functional dependencies\n$A \rightarrow B,\; B \rightarrow C,\; C \rightarrow D,\; D \rightarrow E,\; A \rightarrow E$, decompose $R$ into BCNF. How many relations result from the decomposition?

Correct A. 4

B. 3

C. 6

D. 5

Correct Answer: A

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Question 9 View Details

A document contains $1200$ words. With single line spacing and standard margins, an average page holds $250$ words. If the line spacing is changed to 1.5 and the margins are increased so that each page can hold 15% fewer words, how many pages are required to print the document? (Round up to the next whole page.)

A. 5

B. 7

C. 8

Correct D. 6

Correct Answer: D

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Question 10 View Details

A company owns the network $192.168.0.0/24$. It needs subnets for five departments, each requiring at least 30 usable host addresses. Using VLSM, assign the subnets sequentially and give the first usable IP address of the third subnet.

Correct A. 192.168.0.65

B. 192.168.0.97

C. 192.168.0.129

D. 192.168.0.33

Correct Answer: A

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Question 11 View Details

A system requires passwords of length 8. Each character can be an uppercase letter (26), a lowercase letter (26), a digit (10) or one of 10 special symbols, giving a total character set of 72. The policy mandates that a password must contain at least one uppercase letter, at least one digit, and at least one special symbol. (a) How many distinct passwords satisfy the policy? (b) If an attacker can test $10^{9}$ passwords per second, how many years (to two decimal places) would be required to exhaust the entire password space? (c) The security guideline requires a minimum resistance of 100 years. Does the policy meet this requirement? Answer "Yes" or "No" and give the computed time.

A. Yes; about 0.01 years (≈3.7 days)

B. No; about 1 year (≈365 days)

Correct C. No; about 0.01 years (≈3.7 days)

D. No; about 0.001 years (≈0.37 days)

Correct Answer: C

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Question 12 View Details

The 8‑bit two's complement binary number $11010110$ is stored in memory. (a) Determine its decimal value. (b) Add the decimal integer 5 to this value and give the resulting 8‑bit two's complement binary representation.

Correct A. -37

B. 37

C. -39

D. -35

Correct Answer: A

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Question 13 View Details

Consider a relation R(A,B,C,D) with functional dependencies: $A \rightarrow B$, $B \rightarrow C$, and $A \rightarrow D$. (a) Identify all candidate keys of R. (b) State the highest normal form (1NF, 2NF, 3NF, BCNF) that R satisfies. (c) If R is not in BCNF, decompose it into a set of BCNF relations.

A. Candidate key: {A}. Highest normal form: not in 2NF (so not 3NF). BCNF decomposition: R1(A,D) and R2(B,C).

B. Candidate key: {A,B}. Highest normal form: 2NF. BCNF decomposition: R1(A,B) and R2(B,C,D).

C. Candidate key: {A}. Highest normal form: 3NF. BCNF decomposition: R1(A,B) and R2(B,C,D).

Correct D. Candidate key: {A}. Highest normal form: not in 3NF (so not BCNF). BCNF decomposition: R1(B,C) and R2(A,B,D).

Correct Answer: D

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Question 14 View Details

A presentation consists of 20 slides. Slides 1-5 are introductory slides shown for 30 s each. Slides 6-15 are content slides; each has a base display time of 90 s and contains a video that lasts 20 % of the base time, which must be played in addition to the base time. Slides 16-20 are summary slides shown for 45 s each. Between every pair of consecutive slides a transition animation of 2 s is used. The presenter wants the total presentation time not to exceed 25 minutes. Determine whether the current timing plan satisfies this limit. If it does not, calculate the minimum reduction (in seconds) required in the average display time of the content slides (keeping all other times unchanged) so that the total time is exactly 25 minutes.

Correct A. Fits; 7 seconds spare (no reduction needed).

B. Does not fit; need reduction of 12 seconds.

C. Fits; 3 seconds spare (no reduction needed).

D. Does not fit; need reduction of 7 seconds.

Correct Answer: A

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Question 15 View Details

A sample of 50 students records their weekly study hours (X) and exam scores (Y). The sample mean of X is 12 hours with variance $s_{x}^{2}=9$. The mean of Y is 78 with variance $s_{y}^{2}=64$. The sum of products $\sum (X_{i}-\bar X)(Y_{i}-\bar Y)$ equals 180. (a) Compute the Pearson correlation coefficient $r$. (b) Determine the least‑squares regression line predicting Y from X in the form $\hat Y = a + bX$. (c) At the 5 % significance level, test whether the slope $b$ differs from zero (use a two‑tailed t‑test with $n-2$ degrees of freedom). State the conclusion.

A. r≈0.30; regression line $\hat Y = 70.00 + 0.55X$; slope significant at 5% (reject H0).

B. r≈0.45; regression line $\hat Y = 68.50 + 0.80X$; slope significant at 5% (reject H0).

C. r≈-0.12; regression line $\hat Y = 75.20 - 0.20X$; slope not significant at 5% (fail to reject H0).

Correct D. r≈0.153; regression line $\hat Y = 73.10 + 0.41X$; slope not significant at 5% (fail to reject H0).

Correct Answer: D

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Question 16 View Details

A computer has a $12$-bit address bus and a $16$-bit data bus. What is the maximum amount of addressable memory in kilobytes (KB)?

A. 4 KB

Correct B. 8 KB

C. 16 KB

D. 2 KB

Correct Answer: B

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Question 17 View Details

A password policy requires passwords of length 8. The allowed character set consists of 26 uppercase letters, 26 lowercase letters, 10 digits, and 12 special symbols. A valid password must contain at least one digit and at least one special symbol. (a) How many different passwords satisfy the policy? (b) Assuming an attacker makes five distinct random guesses, what is the probability that the attacker guesses the correct password on one of those attempts?

A. approximately 2.3×10⁻¹⁴

B. approximately 5.0×10⁻¹⁴

C. approximately 1.1×10⁻¹³

Correct D. approximately 1.1×10⁻¹⁴

Correct Answer: D

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Question 18 View Details

An IT support system relies on three independent components: a server (reliability 0.99), an uninterruptible power supply (UPS) (reliability 0.98), and a network switch (reliability 0.97). The system functions if at least two of the three components are operational. What is the probability that the system experiences at least one failure during a 365‑day year, assuming daily independency?

A. 0.312

B. 0.345

Correct C. 0.328

D. 0.298

Correct Answer: C

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Question 19 View Details

Three processes arrive for CPU scheduling as follows: P1 arrives at time 0 ms with CPU burst 10 ms, P2 arrives at time 2 ms with burst 6 ms, and P3 arrives at time 4 ms with burst 8 ms. Using Round‑Robin scheduling with a time quantum of 4 ms and assuming no context‑switch overhead, what is the average waiting time of the three processes (in milliseconds)?

Correct A. 34/3

B. 36\/3

C. 31\/3

D. 33\/3

Correct Answer: A

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Question 20 View Details

A company stores employee data in a table EMP with attributes EmpID (int, 4 bytes), Name (varchar, average length 12 characters), DeptID (int, 4 bytes), Salary (decimal, 8 bytes), and HireDate (date, 4 bytes). The table is in 1NF and contains 5 000 employee records. To achieve 3NF, the table is decomposed into EMP (EmpID, Name, DeptID, Salary, HireDate) and DEPT (DeptID, DeptName) where DeptName is a varchar with average length 15 characters. Assume each varchar field uses actual length plus 1 byte overhead, and each row incurs a 2‑byte record header. There are 20 distinct departments. Calculate the total storage required for the two tables, expressed in megabytes (MB) to three decimal places.

Correct A. 0.167

B. 0.200

C. 0.250

D. 0.150

Correct Answer: A

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Question 21 View Details

A system has three processes $P_1,P_2,P_3$ and two resource types $R_A,R_B$. The total resources are $R_A=10$ and $R_B=8$. The current allocation is $P_1:(3,2), P_2:(2,1), P_3:(2,2)$ and the maximum demand is $P_1:(6,4), P_2:(5,3), P_3:(3,5)$. Process $P_2$ requests an additional $(2,1)$ units of $(R_A,R_B)$. Using the Banker's algorithm, can this request be granted while keeping the system in a safe state?

Correct A. Yes, the request can be granted while keeping the system in a safe state.

B. No, the request cannot be granted because it would lead to an unsafe state.

C. Yes, the request can be granted, but the system would become deadlocked.

D. No, the request must be denied to maintain system safety.

Correct Answer: A

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Question 22 View Details

A presentation consists of 20 slides. Each slide contains two images of size 800 KB each and a 30‑second video clip encoded at 4 Mbps. The presentation also includes a 5 MB audio track. The final file must not exceed 50 MB. Determine whether the presentation meets the size limit. If it exceeds, calculate the minimum compression ratio (to three decimal places) that must be applied to the video clips so that the total size is at most 50 MB.

A. 0.754

B. 0.923

Correct C. 0.867

D. 0.812

Correct Answer: C

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Question 23 View Details

Convert the decimal number 156 to binary and then to hexadecimal.

A. Binary: 10011101; Hexadecimal: 9D

B. Binary: 10011000; Hexadecimal: 98

Correct C. Binary: 10011100; Hexadecimal: 9C

D. Binary: 11001100; Hexadecimal: CC

Correct Answer: C

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Question 24 View Details

A word‑processing document uses Times New Roman 12‑pt font with 1.5 line spacing on A4 paper (21 cm × 29.7 cm). The top and bottom margins are 2.5 cm each, and the left and right margins are 2 cm each. On average, a line contains 65 characters, and the average word consists of 5 characters plus a space (6 characters per word). How many pages are required to type a report of 12 000 words? Assume that only whole lines can be used on a page.

A. 34

B. 28

C. 30

Correct D. 32

Correct Answer: D

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Question 25 View Details

In a spreadsheet, column A lists months 1 to 12. Column B records the sales (in Naira) for each month. The sales for the first six months are: Jan 80 000, Feb 95 000, Mar 110 000, Apr 105 000, May 120 000, Jun 130 000; the remaining months are currently 0. Column C contains the cumulative sales up to that month, using the formula $=SUM($B$1:B_n)$ for row n. The company's annual sales target is 1 200 000 Naira. What is the cumulative sales after June, and what average monthly sales must be achieved in the remaining six months to meet the target? Give the average to the nearest Naira.

A. Cumulative sales after June: 600 000 Naira; required average for remaining months: 100 000 Naira

B. Cumulative sales after June: 630 000 Naira; required average for remaining months: 95 000 Naira

Correct C. Cumulative sales after June: 640 000 Naira; required average for remaining months: 93 333 Naira

D. Cumulative sales after June: 650 000 Naira; required average for remaining months: 90 000 Naira

Correct Answer: C

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