Practice neco data_processing 2019 Past Questions

Question 1 View Details

Table Employees has 120 records, each with fields EmpID, DeptID, Salary. Table Departments has 8 records with fields DeptID, ManagerID, Budget. Each department employs exactly 15 employees. Only departments whose Budget exceeds \(\text{\₦}500{,}000\) are to be considered. From the Employees table, select those with Salary greater than \(\text{\₦}70{,}000\) and perform a natural join with the qualifying Departments. How many rows are returned by the query?

A. 15

B. 45

C. 60

Correct D. 30

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 2 View Details

A spreadsheet records sales (in thousands of Naira) for six transactions as follows:\n- Region: North, Sales: 48\n- Region: South, Sales: 62\n- Region: East, Sales: 35\n- Region: West, Sales: 55\n- Region: North, Sales: 80\n- Region: East, Sales: 45\nCommission rules are:\n* For North and South: 5% on the first \(50\) thousand, and 7% on any amount above \(50\) thousand.\n* For East and West: 6% on the first \(40\) thousand, and 8% on any amount above \(40\) thousand.\nCalculate the total commission payable for all six transactions, giving your answer in thousand Naira to two decimal places.

A. 19.20

B. 17.64

C. 20.05

Correct D. 18.84

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 3 View Details

A company faces an annual expected loss of \(1{,}500{,}000\) Naira if a data breach occurs. The current probability of a breach is \(0.08\). Two security measures are available:\n- Firewall: cost \(200{,}000\) Naira, reduces breach probability to \(0.03\).\n- Employee training: cost \(120{,}000\) Naira, reduces breach probability to \(0.05\).\nCompany policy requires implementing at least one of the measures, and the total security budget cannot exceed \(300{,}000\) Naira. For each feasible option, compute the total expected annual cost (security cost plus expected loss). Which option gives the minimum total expected cost, and what is that cost?

A. Firewall only; total expected cost = 245,000 Naira

B. Employee training only; total expected cost = 210,000 Naira

C. Both measures; total expected cost = 320,000 Naira

Correct D. Employee training only; total expected cost = 195,000 Naira

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 4 View Details

A survey of daily internet data usage (in GB) for seven households gave the values: 12, 18, 22, 27, 33, 40, 48. An internet service provider offers two monthly plans:\n- Plan A: a fixed fee of \(5{,}000\) Naira for unlimited data.\n- Plan B: a fixed fee of \(1{,}500\) Naira plus \(200\) Naira per GB used.\nA household that uses data equal to the 75th percentile of the surveyed usage wants to choose the cheaper plan. Determine the 75th percentile usage and indicate which plan is cheaper for that household, giving the monthly cost under the chosen plan.

Correct A. Plan A (5,000 Naira)

B. Plan B (9,500 Naira)

C. Plan A (5,500 Naira)

D. Plan B (5,000 Naira)

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 5 View Details

Simplify the Boolean function \(F = (A + B)(\overline{A} + C)(B + \overline{C})\). Obtain a minimal sum‑of‑products (SOP) expression and state how many literals are saved compared with the original expression.

A. 4

B. 1

Correct C. 2

D. 3

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 6 View Details

An enterprise uses two subscription models for its cloud service. Model A: a fixed monthly fee of N30 and a charge of N0.05 per transaction. Model B: a fixed monthly fee of N20. For each month, the first 150 transactions are charged at N0.07 each and any transaction beyond 150 is charged at N0.04 each. The number of transactions each month follows an arithmetic progression: the first month has \(120\) transactions and each subsequent month increases by \(15\) transactions. Calculate the total annual cost for each model and state which model is cheaper and by how much (in Naira).

A. Model B is cheaper by N85.20

Correct B. Model B is cheaper by N91.65

C. Model A is cheaper by N12.35

D. Model B is cheaper by N102.50

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 7 View Details

A school processes exam results manually. For each of the 200 students, data entry takes \(5\) minutes, verification takes \(2\) minutes and report generation takes \(1\) minute. A new computer system automates data entry (0 minutes) but adds a system‑check of \(0.5\) minute per student and requires a fixed setup time of \(30\) minutes for the whole batch. Identify the stage of the data‑processing cycle represented by each activity and compute the total time saved in minutes when the computer system is used.

A. 1030

B. 870

C. 1150

Correct D. 1270

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 8 View Details

The database has two tables. \(Students(StudentID, Name, Age, Dept)\) and \(Enrolments(StudentID, CourseCode, Grade)\). Write a relational algebra expression that returns the names of students who belong to the Computer Science department and have obtained grade \('A'\) in at least two different courses. Given that the \(Students\) table contains 120 CS students and that 40 of these students satisfy the grade condition, how many names will the query return?

A. 120

B. 20

C. 80

Correct D. 40

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 9 View Details

A 7‑bit Hamming (7,4) code is used with even parity. The original 4 data bits are \(d_1d_2d_3d_4 = 1011\). Parity bits are placed at positions 1, 2 and 4. The transmitted code is therefore \(0110011\). During transmission, bit position 5 is flipped. The received code is \(0110111\). Using syndrome decoding, identify the erroneous bit, correct the code, and state the original 4 data bits.

A. 1111

B. 0010

Correct C. 1011

D. 1001

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 10 View Details

The flowchart below describes an algorithm:\nStart → Input integer \(n\) → Is \(n = 1\)?\n Yes → Output count and Stop\n No → Is \(n\) even?\n Yes → Set \(n = n/2\)\n No → Set \(n = 3n + 1\)\nIncrement count and repeat.\nIf the input integer is \(6\), how many iterations does the algorithm perform before it stops?

A. 7

B. 9

C. 10

Correct D. 8

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 11 View Details

Consider a relation R(A,B,C,D) with functional dependencies \(A \rightarrow B\), \(BC \rightarrow D\), and \(C \rightarrow A\). Determine (i) the candidate key(s) of R, (ii) the highest normal form that R satisfies, and (iii) after decomposing R into BCNF, how many relations are obtained.

Correct A. C, 2NF, 3

B. C, 3NF, 3

C. C, 2NF, 2

D. A, 2NF, 3

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 12 View Details

A spreadsheet records monthly sales (in units) of three products A, B and C for the first six months. The sales of A and B are fixed: \(A: 1200, 1300, 1250, 1400, 1350, 1500\); \(B: 800, 850, 900, 950, 1000, 1100\). The total sales recorded for each month (column D) are \(3000, 3200, 3400, 3600, 3800, 4000\) respectively.\n\n(i) Determine the sales of product C for each month.\n(ii) From month 4 onward a promotion increases product C sales by 5%. After this increase, in which month does the overall total first exceed 3800 units?

A. April

Correct B. May

C. June

D. July

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 13 View Details

A relation STUDENT has attributes \(SID\), \(Name\), \(Email\) and \(Phone\). The following uniqueness constraints are given: each \(SID\) is unique and each \(Email\) is unique. Identify all candidate keys and state which attribute is normally chosen as the primary key.

A. SID (candidate keys: SID)

B. SID (candidate keys: SID, Phone)

C. Email (candidate keys: SID, Email)

Correct D. SID (candidate keys: SID, Email)

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 14 View Details

Convert the decimal number 156 to its binary representation using the successive division method.

A. 10011101

B. 10011011

Correct C. 10011100

D. 10100100

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 15 View Details

The table EMP contains the columns EmpID, Dept and Salary with the following data:\n\nEmpID | Dept | Salary\n1 | A | 5000\n2 | A | 7000\n3 | B | 6000\n4 | B | 8000\n5 | C | 4000\n6 | C | 5000\n7 | D | 9000\n\nUsing SQL, list the department(s) whose average salary is greater than the overall average salary of the company.

A. B and C

B. A and D

Correct C. B and D

D. A and C

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 16 View Details

In a data processing project, the total time spent on the four stages of the data processing cycle (Input, Process, Output, Storage) is 120 minutes. The time spent on the Process stage is twice the time spent on the Input stage. The Output stage takes 10 minutes less than the Storage stage. The Input and Storage stages together take 50 minutes. Determine the time (in minutes) spent on each of the four stages.

A. Input = 35 min, Process = 70 min, Output = 5 min, Storage = 10 min

B. Input = 25 min, Process = 50 min, Output = 15 min, Storage = 30 min

C. Input = 20 min, Process = 40 min, Output = 20 min, Storage = 40 min

Correct D. Input = 30 min, Process = 60 min, Output = 10 min, Storage = 20 min

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 17 View Details

A text file is stored using Unicode where each character occupies 2 bytes. The file size is 3 kilobytes. How many characters are stored in the file?

A. 3072

B. 1530

Correct C. 1536

D. 1500

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 18 View Details

A user has a monthly data plan of 5 GB costing \\(\text{₦}2,000\\). He uses three apps: App X consumes 40\% of his data, App Y consumes 35\%, and App Z consumes the remainder. The provider charges overage at \\(\text{₦}150\\) per additional 100 MB. During the month, the user exceeds his plan by 600 MB, and the overage is entirely due to App Z. The provider offers a 20\% discount on the overage charge for App Z. Determine the total amount the user pays for the month.

A. ₦2750

B. ₦2900

C. ₦2500

Correct D. ₦2720

Correct Answer: D

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 19 View Details

A survey collected ages (in years) of 20 participants: 22, 35, 27, 19, 45, 33, 28, 31, 120, 29, 24, 38, 26, 23, 0, 34, 30, 27, 25, 32. Ages less than 5 or greater than 100 are considered invalid. Additionally, any age that appears more than twice is considered a duplicate and only the first occurrence is kept. After cleaning the data, how many valid age entries remain?

A. 17

B. 20

Correct C. 18

D. 19

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 20 View Details

A spreadsheet records monthly sales (in units) of three products over six months as follows:\n\nMonth | Product A | Product B | Product C\nJan | 1200 | 800 | 500\nFeb | 1350 | 950 | 600\nMar | 1500 | 1100 | 550\nApr | 1600 | 1050 | 650\nMay | 1580 | 1150 | 700\nJun | 1700 | 1200 | 750\n\nCalculate the total sales for each product over the six months. Identify the month with the highest total sales across all products. For that month, determine which product contributed the most to the total and compute the percentage increase of that product's sales from the previous month, rounded to one decimal place.

Correct A. June; Product A; 7.6\%

B. May; Product A; 7.6\%

C. June; Product A; 6.9\%

D. June; Product B; 7.6\%

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 21 View Details

In a data‑processing cycle, the input step takes 2 s, processing 5 s, storage 1 s and output 3 s. After each cycle a feedback step is performed only if an error is detected. The probability that an error occurs in a cycle is 0.2. If the expected total time for one complete cycle (including possible feedback) is 12 s, find the duration \(f\) (in seconds) of the feedback step.

Correct A. 5

B. 6

C. 8

D. 4

Correct Answer: A

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 22 View Details

A text file contains only uppercase letters and spaces. Each character is stored using an 8‑bit ASCII code plus an even‑parity bit (1 extra bit). The file system adds a fixed 512‑byte header. The total size of the file on disk is 9,512 bytes. How many characters are stored in the file?

A. 10000

Correct B. 8000

C. 7200

D. 9000

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 23 View Details

Simplify the Boolean expression \(F = (A + B')(C + D')(A' + C')\) using Boolean algebra. Then determine the minimum number of two‑input NAND gates required to implement the simplified function.

A. 15

Correct B. 14

C. 12

D. 18

Correct Answer: B

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 24 View Details

A storage system records the time taken for a data‑access operation. A sequential access to the next block takes 5 ms. A random access consists of an unknown seek time \(S\) (ms) plus an unknown rotational latency \(R\) (ms). 70 % of accesses are sequential and 30 % are random. The measured average access time is 9 ms. Find the sum \(S+R\) (in milliseconds) of the unknown times.

A. 12.50

B. 20.00

Correct C. 18.33

D. 15.00

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

Question 25 View Details

A file uses a two‑level indexed organization. Each first‑level index block can hold 64 pointers to second‑level index blocks. Each second‑level index block can hold 128 pointers to data blocks. Each data block stores 256 records. The file contains 10,000,000 records. What is the minimum number of first‑level index blocks required to index the entire file?

A. 7

B. 6

Correct C. 5

D. 4

Correct Answer: C

Want to see the full step-by-step solution? Unlock AI Explanation & Analytics

neco 2019 data_processing | Objective

Master the Exam!

Help others prepare! Share this practice hub: