Practice neco computer_studies 2017 Past Questions

Question 1 View Details

The first electronic general‑purpose computer, ENIAC, was completed in 1945. The first commercially available computer, UNIVAC I, was delivered to the U.S. Census Bureau in 1951. Which of these computers was operational earlier?

A. UNIVAC I

Correct B. ENIAC

C. IBM 701

D. EDVAC

Correct Answer: B

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Question 2 View Details

An input device was invented in 1964 by Douglas Engelbart and later improved in 1981 with the introduction of the optical sensor. What is the name of this device?

A. Joystick

B. Trackball

C. Touchpad

Correct D. Computer mouse

Correct Answer: D

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Question 3 View Details

A file of 150 MB is to be transferred over a network with a bandwidth of 12 Mbps. The network incurs a protocol overhead of 15 % of the raw data rate, so the effective bandwidth is $12 \times (1-0.15)=10.2$ Mbps. Additionally, the connection experiences a latency of 80 ms before transmission starts. What is the total transfer time in seconds, rounded to two decimal places?

A. 14.79

B. 117.65

C. 100.08

Correct D. 117.73

Correct Answer: D

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Question 4 View Details

A program contains a loop that runs $i$ from 1 to $n$, and inside it a nested loop that runs $j$ from $i$ to $n$. Inside the inner loop, a constant‑time operation is performed. Derive the Big‑O time complexity of the program in terms of $n$.

Correct A. O(n^2)

B. O(n^3)

C. O(n log n)

D. O(n)

Correct Answer: A

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Question 5 View Details

Consider the following Python code:\n\n```python\ntotal = 0\nfor k in range(1, 7):\n if k % 2 == 0:\n total += k**2\n else:\n total -= k\nprint(total)\n```\n\nWhat value is printed when the program is executed?

A. 55

B. 45

Correct C. 47

D. 41

Correct Answer: C

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Question 6 View Details

Consider the following Python program: ```python total = 0 for i in range(1, 6): for j in range(i, 6): if (i + j) % 3 == 0: total += i * j print(total) ``` What integer value is displayed when the program is executed?

A. 45

B. 40

C. 48

Correct D. 44

Correct Answer: D

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Question 7 View Details

An 8‑bit data word $10110010$ is to be transmitted using even parity. a) Determine the parity bit that must be added. b) If during transmission the third bit from the left flips, will the receiver detect an error? Answer "Yes" or "No".

A. Parity bit = 1; Error detected = Yes

B. Parity bit = 1; Error detected = No

C. Parity bit = 0; Error detected = No

Correct D. Parity bit = 0; Error detected = Yes

Correct Answer: D

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Question 8 View Details

A sorting program can use either Algorithm A with time complexity $O(n \log_2 n)$ or Algorithm B with time complexity $O(n^{2})$. For an input size of $n = 1024$, approximate the number of elementary operations each algorithm would perform (assume the constants are 1) and state which algorithm is faster and by what integer factor (rounded to the nearest whole number).

A. Algorithm B; 204

Correct B. Algorithm A; 102

C. Algorithm B; 102

D. Algorithm A; 204

Correct Answer: B

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Question 9 View Details

In a web page, the following CSS rules are defined: ```css p { color: red; } .intro { color: blue; } #main p.intro { color: green; } ``` A paragraph element has the class `intro` and is placed inside a `<div>` element whose id is `main`. Which color will be applied to the paragraph when the page is rendered?

Correct A. green

B. blue

C. red

D. black

Correct Answer: A

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Question 10 View Details

In a spreadsheet, cell $A1$ contains 5, $A2$ contains 7, $A3$ contains 9, $A4$ contains 4, and cell $C1$ contains 3. Cell $B2$ has the formula `=A1*$C$1`. If this formula is copied down to cells $B3$, $B4$ and $B5$, what values will appear in cells $B2$ through $B5$ respectively? Provide the four numbers separated by commas.

A. 15, 21, 27, 15

Correct B. 15, 21, 27, 12

C. 15, 0, 0, 0

D. 5, 7, 9, 4

Correct Answer: B

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Question 11 View Details

A computer's power supply is rated at 450 W. The CPU consumes 95 W, the motherboard 45 W, the hard drive 10 W, and each of two fans consumes 5 W. The remaining components together consume 80 W. Determine whether the power supply provides at least a $20\%$ head‑room above the total power consumption.

A. Insufficient

B. No

Correct C. Yes

D. Uncertain

Correct Answer: C

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Question 12 View Details

Consider a relation R(E, P, S, D, M) with the functional dependencies: $E \rightarrow S$, $D \rightarrow M$, $(E,P) \rightarrow D$, $(E,P) \rightarrow S$.\n(a) Identify all candidate keys of R.\n(b) State whether R is in Third Normal Form (3NF). If it is not, decompose R into a set of relations that are in 3NF using the synthesis algorithm. List the resulting relations with their attributes.

A. R1(E,S); R2(D,M); R3(E,P)

Correct B. R1(E,S); R2(D,M); R3(E,P,D)

C. R1(E,S,D); R2(D,M); R3(E,P)

D. R1(E,P); R2(D,M); R3(E,S)

Correct Answer: B

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Question 13 View Details

A company has been allocated the Class B network 172.16.0.0/16. It needs subnets for five departments, each requiring at least 2000 usable host addresses. Determine:\n1. The subnet mask that satisfies the host requirement.\n2. The maximum number of subnets that can be created with that mask.\n3. The network address range (first and last usable host addresses) for the first department's subnet.

A. Subnet mask /21; 32 subnets; usable hosts 172.16.0.2 - 172.16.7.255

B. Subnet mask /22; 64 subnets; usable hosts 172.16.0.1 - 172.16.3.254

Correct C. Subnet mask /21; 32 subnets; usable hosts 172.16.0.1 - 172.16.7.254

D. Subnet mask /20; 16 subnets; usable hosts 172.16.0.1 - 172.16.15.254

Correct Answer: C

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Question 14 View Details

The following schedule S involves three transactions T1, T2 and T3:\n- T1: R(A), W(A), R(B)\n- T2: W(B), R(C)\n- T3: W(C), R(A)\nAll operations are performed in the order listed above (first all of T1, then T2, then T3). Determine whether schedule S is conflict‑serializable. If it is, give one equivalent serial order of the transactions; if it is not, state that it is not conflict‑serializable.

A. Conflict‑serializable: T2 → T3 → T1

B. Conflict‑serializable: T1 → T2 → T3

C. Conflict‑serializable: T3 → T1 → T2

Correct D. Not conflict‑serializable

Correct Answer: D

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Question 15 View Details

Consider the following HTML fragment and CSS rules.\nHTML:\n```html\n<div class=\"container\">\n <p id=\"para1\" class=\"text\" style=\"color: purple;\">Hello World</p>\n</div>\n```\nCSS:\n```css\n.container p { color: blue !important; }\n#para1 { color: red; }\np.text { color: green; }\ndiv > p { color: yellow; }\```\n(a) What is the final text colour of the paragraph when rendered in a browser?\n(b) The \`.container\` element has a declared width of 800 px, padding of 20 px on each side, a border of 5 px on each side, and a margin of 10 px on each side. Inside it, a child \`<div class=\"box\">\` has \`width: 50%;\` and padding of 10 px on each side and a border of 2 px on each side. Assuming the default \`box‑sizing: content-box\`, calculate the total rendered width (including padding and border) of the \`.box\` element.

A. a) yellow; b) 408 px

B. a) green; b) 440 px

Correct C. a) blue; b) 424 px

D. a) red; b) 400 px

Correct Answer: C

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Question 16 View Details

A company uses the following spreadsheet formula to compute an employee's net bonus (in naira): Base bonus = IF(sales>=60000,0.12*sales, IF(sales>=40000,0.09*sales, IF(sales>=20000,0.06*sales,0.04*sales))) Region bonus = VLOOKUP(region, {North,0.025; South,0.020; East,0.022; West,0.021}, 2, FALSE)*sales Gross bonus = Base bonus + Region bonus Tax rate = IF(Gross<=3000,0.05, IF(Gross<=5000,0.08,0.12)) Net bonus = Gross bonus * (1 - Tax rate) If an employee in the West region records sales of \$45,000\$ naira, what is the net bonus (rounded to two decimal places)?

Correct A. 4595.40

B. 4554.00

C. 4395.60

D. 4745.25

Correct Answer: A

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Question 17 View Details

A company has been allocated the Class B network \$172.16.0.0/16\$. It must create subnets for three departments using VLSM. The Admin department needs at least 120 hosts, Sales at least 60 hosts, and R\\&D at least 30 hosts. Subnets are to be assigned in the order Admin, Sales, R\\&D. Determine the subnet mask (in CIDR notation) for each department and give the first usable IP address of each subnet.

A. Admin: 172.16.0.0\/26, first usable 172.16.0.1; Sales: 172.16.0.64\/27, first usable 172.16.0.65; R\&D: 172.16.0.96\/28, first usable 172.16.0.97

B. Admin: 172.16.0.0\/25, first usable 172.16.0.2; Sales: 172.16.0.128\/26, first usable 172.16.0.130; R\&D: 172.16.0.192\/27, first usable 172.16.0.194

Correct C. Admin: 172.16.0.0/25, first usable 172.16.0.1; Sales: 172.16.0.128/26, first usable 172.16.0.129; R\&D: 172.16.0.192/27, first usable 172.16.0.193

D. Admin: 172.16.0.0\/24, first usable 172.16.0.1; Sales: 172.16.1.0\/25, first usable 172.16.1.1; R\&D: 172.16.1.128\/26, first usable 172.16.1.129

Correct Answer: C

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Question 18 View Details

A file of size \$2\$ MB needs to be transferred from Host A to Host B over a path consisting of three serial links. Each link has a bandwidth of \$4\$ Mbps and a propagation delay of \$10\$ ms. The file is segmented into packets of \$1{,}500\$ bytes. Assuming store‑and‑forward switching, calculate the total time (in seconds, to three decimal places) required for the complete file to reach Host B.

A. 4.733

Correct B. 4.233

C. 5.233

D. 3.733

Correct Answer: B

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Question 19 View Details

A text file contains \$10{,}000\$ characters, each stored as an 8‑bit ASCII code. After compression with a simple run‑length encoding (RLE) scheme that stores each run as a pair (character, count) where the count occupies 8 bits, the file size becomes \$6{,}200\$ bytes. Assuming the compressed file consists solely of such pairs, determine (a) the compression ratio expressed as a percentage, and (b) the average run length (in characters, to two decimal places).

A. 62%; 3.12

B. 63%; 3.30

Correct C. 62%; 3.23

D. 61%; 3.23

Correct Answer: C

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Question 20 View Details

Consider the following relational schemas: Employee(EmpID, Name, DeptID, Salary) (EmpID is the primary key) Dept(DeptID, DeptName, ManagerID) (ManagerID references EmpID) The data are: Employee: 1, Alice, 10, 50000 2, Bob, 10, 60000 3, Carol, 20, 55000 4, Dave, 20, 65000 5, Eve, 30, 70000 Dept: 10, Sales, 1 20, R\\&D, 3 30, HR, 5 Write a relational algebra expression that returns the names of employees who earn more than the average salary of their department and also earn more than the salary of their department's manager. Then state the result of the expression for the data given.

A. Bob, Eve

B. Alice, Carol

Correct C. Bob, Dave

D. Alice, Dave

Correct Answer: C

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Question 21 View Details

Given the Python function below, what integer value does it return when called with $N = 10$?\n\n```python\ndef mystery(N):\n total = 0\n i = 1\n while i <= N:\n if i % 2 == 0:\n j = i\n while j > 0:\n total += j % 5\n j -= 3\n else:\n total += i\n i += 1\n return total\n```

A. 45

Correct B. 48

C. 52

D. 60

Correct Answer: B

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Question 22 View Details

In a school computer lab there are 25 PCs, each storing $500$ MB of user data. A daily incremental backup records only the changes, which on average amount to $2\%$ of the total data stored on a PC. A full backup, performed once every 7 days, stores all the data on all PCs. Over a 30‑day month, what total amount of backup data (in gigabytes, GB) is stored?

A. 58.0

B. 55.5

Correct C. 56.5

D. 68.8

Correct Answer: C

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Question 23 View Details

Relation $R(A,B,C,D)$ has the functional dependencies $A \rightarrow B$, $BC \rightarrow D$ and $D \rightarrow A$. If $R$ is decomposed into Boyce‑Codd Normal Form (BCNF) using the standard decomposition algorithm, how many relations result from the decomposition?

A. 2

Correct B. 3

C. 5

D. 4

Correct Answer: B

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Question 24 View Details

The following pseudo‑code is executed with a positive integer $n$.\n\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```\n\nExpress the final value of $count$ as a summation and then give its numerical value when $n = 10$.

Correct A. 27

B. 25

C. 28

D. 30

Correct Answer: A

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Question 25 View Details

A password policy requires that an 8‑character password contain at least one uppercase letter (26 possibilities), one lowercase letter (26 possibilities), one digit (10 possibilities) and one special character (10 possibilities). Characters may be repeated and any of the 72 allowed characters (26+26+10+10) may appear in any position. Using the inclusion‑exclusion principle, how many distinct passwords satisfy the policy? Give your answer as a simplified expression.

Correct A. $72^{8} - 2\cdot46^{8} - 2\cdot62^{8} + 20^{8} + 4\cdot36^{8} + 52^{8} - 2\cdot10^{8} - 2\cdot26^{8}$

B. $72^{8} - 2\cdot46^{8} - 2\cdot62^{8} + 4\cdot36^{8} + 52^{8} - 2\cdot10^{8} - 2\cdot26^{8}$

C. $72^{8} - 2\cdot46^{8} + 2\cdot62^{8} + 20^{8} + 4\cdot36^{8} + 52^{8} - 2\cdot10^{8} - 2\cdot26^{8}$

D. $72^{8} - 2\cdot46^{8} - 2\cdot62^{8} + 20^{8} + 2\cdot36^{8} + 52^{8} - 2\cdot10^{8} - 2\cdot26^{8}$

Correct Answer: A

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