Practice city guilds model questions vol1 information_technology 2017 Past Questions

Question 1 View Details

A company has been allocated the address block 192.168.64.0/20. It needs three sub‑nets for departments A, B and C requiring at least 3000, 1200 and 500 hosts respectively. Using VLSM, what is the subnet mask (in dotted‑decimal notation) for the subnet assigned to department B and what is that subnet's network address?

A. 255.255.252.0, 192.168.72.0

B. 255.255.240.0, 192.168.64.0

C. 255.255.254.0, 192.168.88.0

Correct D. 255.255.248.0, 192.168.80.0

Correct Answer: D

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Question 2 View Details

A client resolves the domain example.com. The authoritative DNS server returns an A record with TTL 3600 s and the round‑trip time for a query to that server is 150 ms. After 45 min the client requests the same name again (served from cache). After a further 30 min the client's ISP switches to a different DNS resolver that has no cached entry, so the client queries again. Assuming no other queries for example.com occur, what total time in seconds does the client spend waiting for DNS responses across the three queries?

A. 0.15

Correct B. 0.30

C. 0.60

D. 0.45

Correct Answer: B

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Question 3 View Details

A report is to be printed on A4 paper (210 mm × 297 mm) with 2 cm margins on all sides. Each page also has a header and a footer, each occupying 15 mm of vertical space. The document uses a font where each character is 0.5 mm wide and 2.5 mm high (including line spacing). The report contains 85 000 characters (including spaces). Assuming no hyphenation and left‑justified lines, what is the minimum number of pages required to print the report?

A. 5

B. 2

Correct C. 3

D. 4

Correct Answer: C

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Question 4 View Details

In a spreadsheet, cell A1 holds the principal amount P = 150 000 ₦. Cells B1 and C1 contain annual interest rates r₁ = 5 % and r₂ = 7 % respectively, and cell D1 contains the number of years n = 4. The current formula in cell E1 is =P*(1+r1)*(1+r2)*(1+r1)*(1+r2). Replace this with a single formula that uses the POWER function to raise the average annual growth factor to the appropriate power, and state the future value obtained, rounded to the nearest naira.

A. =P*POWER((1+r1)*(1+r2), n\/2) → 185000

B. =P*POWER((1+r1)*(1+r2), n\/2) → 191500

C. =P*POWER((1+r1)*(1+r2), n\/2) → 200000

Correct D. =P*POWER((1+r1)*(1+r2), n/2) → 189338

Correct Answer: D

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Question 5 View Details

Convert the binary numbers 101101₂ and 11011₂ to decimal, add the two decimal values, and give the sum in binary notation.

Correct A. 1001000_2

B. 1000110_2

C. 1001010_2

D. 1001100_2

Correct Answer: A

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Question 6 View Details

A presenter has prepared 20 slides. Each slide is displayed for $45$ seconds. For every third slide an animation adds $10$ seconds, and for every fifth slide a video clip adds $30$ seconds. If a slide is both a multiple of 3 and 5, both additions apply. What is the total presentation time in minutes?

A. 20 minutes

B. 22 minutes

C. 16 minutes

Correct D. 18 minutes

Correct Answer: D

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Question 7 View Details

A process makes $500$ memory references. The TLB hit ratio is $80\%$. Each TLB hit takes $1$ µs, while each miss requires $5$ µs. What is the average memory access time in microseconds?

A. 2.0

B. 2.2

Correct C. 1.8

D. 1.6

Correct Answer: C

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Question 8 View Details

In a spreadsheet, column A lists the quantities sold from Monday to Friday as 12, 15, 9, 20, x units. Column B contains the unit price: \$5 for Monday-Thursday, but on Friday the price is discounted by 20 % (i.e., \$4). Column C computes revenue as A \times B. The total weekly revenue shown in cell C6 is \$500. Find the value of x.

A. 50

B. 60

Correct C. 55

D. 45

Correct Answer: C

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Question 9 View Details

A company has been allocated the address block 192.168.64.0/20. It must create subnets for three departments with the following minimum host requirements: HR - 500 hosts, IT - 2000 hosts, Sales - 300 hosts. Choose the smallest possible CIDR subnet mask for each department and give the first usable IP address of the Sales subnet.

Correct A. 192.168.74.1

B. 192.168.75.1

C. 192.168.73.1

D. 192.168.74.2

Correct Answer: A

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Question 10 View Details

Consider the following Python‑like program: ``` count = 0 for i in range(1, n+1): for j in range(1, i+1): if (i*j) % 3 == 0: count += 1 print(count) ``` If $n = 10$, what value is printed?

A. 24

B. 30

C. 28

Correct D. 27

Correct Answer: D

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Question 11 View Details

What is the minimum number of bits required to represent any integer from $0$ to $150$ inclusive in binary?

A. 9

Correct B. 8

C. 7

D. 10

Correct Answer: B

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Question 12 View Details

A web page contains three images of sizes $120\text{ KB}$, $250\text{ KB}$ and $340\text{ KB}$. Before transmission each image is compressed by 20\% and an HTTP header of $1.5\text{ KB}$ is added to each file. If the connection speed is $2\text{ Mbps}$, what is the total time, in seconds, required to download all three images? Give your answer to two decimal places.

A. 2.75

B. 2.55

Correct C. 2.35

D. 2.15

Correct Answer: C

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Question 13 View Details

Consider a relation $R(A,B,C,D,E)$ with the functional dependencies: $A \rightarrow B$, $C \rightarrow D$, and $BD \rightarrow E$. What is the minimum number of attributes that a candidate key of $R$ can contain?

A. 3

B. 1

Correct C. 2

D. 4

Correct Answer: C

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Question 14 View Details

A packet of $1500$ bytes is transmitted over a link that is $2500$ km long. The link bandwidth is $10$ Mbps and the signal propagation speed is $2\times10^{8}$ m/s. Each router adds a processing delay of $2$ ms and an average queueing delay of $5$ ms.\ (a) Compute the total end‑to‑end delay for the packet.\ (b) If the bandwidth is upgraded to $20$ Mbps while all other parameters remain unchanged, what is the new total delay?\ (c) Which component of the delay is responsible for the greatest reduction when the bandwidth is doubled?

A. (a) 22.5 ms; (b) 21.9 ms; (c) propagation delay

B. (a) 21.0 ms; (b) 20.4 ms; (c) queueing delay

C. (a) 19.8 ms; (b) 19.2 ms; (c) processing delay

Correct D. (a) 20.7 ms; (b) 20.1 ms; (c) transmission delay

Correct Answer: D

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Question 15 View Details

Consider the following function written in a C‑like language:\ \ ``` int f(int n){ int sum = 0; for(int i = 1; i <= n; i++){ int term = i; for(int j = i; j <= n; j++){ term = term * j; } sum = sum + term; } return sum; } ```\ What integer value does the function return when it is called with $n = 4$?

A. 100

B. 64

C. 148

Correct D. 124

Correct Answer: D

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Question 16 View Details

A relation R(A,B,C,D,E) has the functional dependencies: A → B, A → C, BC → D, and D → E. Determine a lossless‑join decomposition of R into BCNF, list the resulting schemas, and state whether the decomposition preserves all functional dependencies.

A. BCNF decomposition: {A,B,C}, {A,D}, {B,E}. The decomposition is lossless‑join and preserves all functional dependencies.

Correct B. BCNF decomposition: {B,C,D}, {A,B}, {A,C}, {A,E}. The decomposition is lossless‑join but does not preserve the dependency D → E.

C. BCNF decomposition: {A,B}, {C,D}, {A,E}. The decomposition is lossless‑join but does not preserve the dependency A → C.

D. BCNF decomposition: {B,C}, {A,D,E}. The decomposition is not lossless‑join and does not preserve the dependency D → E.

Correct Answer: B

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Question 17 View Details

A student must give a 15‑minute presentation that includes a question‑and‑answer period occupying 20 % of the total time. Each slide requires 45 seconds of speaking time and a 5‑second transition to the next slide (no transition after the last slide). What is the maximum number of slides the student can use without exceeding the allotted time?

A. 13

B. 15

Correct C. 14

D. 12

Correct Answer: C

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Question 18 View Details

A company owns the network 192.168.0.0/24 and needs subnets for three departments: Department A requires at least 50 hosts, Department B at least 20 hosts, and Department C at least 10 hosts. Using variable‑length subnet masking (VLSM) and allocating the largest subnet first, assign a subnet to each department, give the network and broadcast addresses for each, and state the remaining unused address block.

A. Department A: 192.168.0.0/26 (hosts 192.168.0.1‑192.168.0.62, broadcast 192.168.0.63); Department B: 192.168.0.96/28 (hosts 192.168.0.97‑192.168.0.110, broadcast 192.168.0.111); Department C: 192.168.0.64/27 (hosts 192.168.0.65‑192.168.0.94, broadcast 192.168.0.95); Unused block: 192.168.0.112/28.

B. Department A: 192.168.0.0/25 (hosts 192.168.0.1‑192.168.0.126, broadcast 192.168.0.127); Department B: 192.168.0.128/26 (hosts 192.168.0.129‑192.168.0.190, broadcast 192.168.0.191); Department C: 192.168.0.192/27 (hosts 192.168.0.193‑192.168.0.222, broadcast 192.168.0.223); Unused block: 192.168.0.224/27.

C. Department A: 192.168.0.0/27 (hosts 192.168.0.1‑192.168.0.30, broadcast 192.168.0.31); Department B: 192.168.0.32/26 (hosts 192.168.0.33‑192.168.0.94, broadcast 192.168.0.95); Department C: 192.168.0.96/28 (hosts 192.168.0.97‑192.168.0.110, broadcast 192.168.0.111); Unused block: 192.168.0.112/28.

Correct D. Department A: 192.168.0.0/26 (hosts 192.168.0.1‑192.168.0.62, broadcast 192.168.0.63); Department B: 192.168.0.64/27 (hosts 192.168.0.65‑192.168.0.94, broadcast 192.168.0.95); Department C: 192.168.0.96/28 (hosts 192.168.0.97‑192.168.0.110, broadcast 192.168.0.111); Unused block: 192.168.0.112/28.

Correct Answer: D

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Question 19 View Details

Historical ticket data for a help‑desk show that 40 % of tickets are hardware issues, 35 % software issues, and 25 % network issues. Average resolution times are 45 min for hardware, 30 min for software, and 60 min for network. If a ticket is escalated to a senior technician (probability of escalation: hardware 20 %, software 10 %, network 30 %), the resolution time after escalation is reduced to 75 % of the original time. Assuming escalations occur as given, what is the expected resolution time for a randomly selected ticket (in minutes, rounded to two decimal places)?

A. 38.75

B. 42.50

Correct C. 41.21

D. 45.00

Correct Answer: C

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Question 20 View Details

Four processes arrive at time 0 with CPU burst times: P1 = 10 ms, P2 = 4 ms, P3 = 6 ms, and P4 = 8 ms. The operating system schedules them using Round‑Robin with a time quantum of 3 ms. Compute the average waiting time of the processes (in milliseconds, to two decimal places).

A. 12.33

Correct B. 14.75

C. 16.50

D. 13.25

Correct Answer: B

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Question 21 View Details

A company records the monthly sales of five employees as follows: A - (12{,}000\) Naira, B - (8{,}500\) Naira, C - (15{,}000\) Naira, D - (4{,}000\) Naira, E - (11{,}000\) Naira. The commission rate is 5 % for sales up to (5{,}000\) Naira, 7 % for sales between (5{,}001\) and (10{,}000\) Naira, and 10 % for sales above (10{,}000\) Naira. After computing each employee's commission, the total commission is taxed: if the total exceeds (2{,}000\) Naira the tax rate is 12 %; otherwise it is 8 %. Determine the net commission payable to all employees (in Naira, to two decimal places).

Correct A. 4043.60

B. 4243.60

C. 3843.60

D. 4043.00

Correct Answer: A

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Question 22 View Details

A manufacturing firm sells a product for $30$ Naira per unit. The variable cost per unit depends on the monthly production quantity $P$: if $P<1000$ the cost is $20$ Naira per unit; if $1000\le P\le2000$ the cost is $18$ Naira per unit; and if $P>2000$ the cost is $15$ Naira per unit. Fixed overhead is $5{,}000$ Naira per month. What is the smallest integer production quantity $P$ that will give a net profit of at least $20{,}000$ Naira?

Correct A. 2001

B. 2100

C. 2000

D. 1999

Correct Answer: A

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Question 23 View Details

Consider the relation STUDENT(CourseID, StudentID, Name, Score, Instructor) where the primary key is $(CourseID, StudentID)$. The functional dependencies are:\n$CourseID \rightarrow Instructor$\n$StudentID \rightarrow Name$\n$(CourseID, StudentID) \rightarrow Score$\n\n(a) Decompose the relation into a set of tables that are in Boyce‑Codd Normal Form (BCNF). How many tables result from the decomposition?\n\n(b) Write an SQL query that returns the names of instructors whose courses have an average student score greater than 85.

A. 3 tables; SELECT DISTINCT I.Instructor FROM R1 AS I JOIN R4 AS S ON I.CourseID = S.CourseID GROUP BY I.CourseID, I.Instructor HAVING AVG(S.Score) >= 85;

Correct B. 3 tables; SELECT DISTINCT I.Instructor FROM R1 AS I JOIN R4 AS S ON I.CourseID = S.CourseID GROUP BY I.CourseID, I.Instructor HAVING AVG(S.Score) > 85;

C. 3 tables; SELECT DISTINCT I.Instructor FROM R1 AS I JOIN R4 AS S ON I.CourseID = S.CourseID GROUP BY I.CourseID, I.Instructor HAVING AVG(S.Score) > 90;

D. 2 tables; SELECT I.Instructor FROM R1 AS I JOIN R4 AS S ON I.CourseID = S.CourseID GROUP BY I.Instructor HAVING AVG(S.Score) > 85;

Correct Answer: B

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Question 24 View Details

A system has three processes $P_{1}, P_{2}, P_{3}$ and two resource types $A$ (5 instances) and $B$ (3 instances). The current allocation and maximum demand matrices are:\n\nAllocation:\n$P_{1}: (A=2, B=0)$\n$P_{2}: (A=1, B=1)$\n$P_{3}: (A=0, B=2)$\n\nMaximum:\n$P_{1}: (A=3, B=2)$\n$P_{2}: (A=2, B=2)$\n$P_{3}: (A=2, B=2)$\n\nUsing the Banker's algorithm, determine whether the system is in a safe state. If it is safe, give one possible safe sequence of process execution.

Correct A. Yes, safe; safe sequence: P3 -> P1 -> P2

B. Yes, safe; safe sequence: P2 -> P3 -> P1

C. Yes, safe; safe sequence: P1 -> P2 -> P3

D. No, unsafe; deadlock occurs.

Correct Answer: A

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Question 25 View Details

A word‑processing document contains 120 paragraphs. When the document uses single line spacing (1.0) and a 12 pt font, each paragraph occupies exactly 5 lines of text, and the page can hold 25 lines. The author changes the style to 1.5 line spacing and adds a 6 pt space after each paragraph. With this new spacing the page can hold only 20 lines of text. Additionally, a header of 2 lines is added to every page, reducing the usable lines per page accordingly. Assuming the 6 pt after‑paragraph space is equivalent to half a line, how many pages are required for the document after the formatting changes? Give the answer as a whole number of pages.

A. 41

B. 35

C. 38

Correct D. 37

Correct Answer: D

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