WAEC SSCE - Computer Studies - 2019

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A NAND gate is a logic gate that produces an output of 0 only when all its inputs are 1. In all other cases, the output is 1. So, if any of the inputs is 0, the output will be 1. If all the inputs are 1, the output will be 0. To put it another way, the NAND gate behaves like an "inverted AND" gate. It produces an output of 1 when any of the inputs is 0, and only produces an output of 0 when all the inputs are 1. This behavior makes the NAND gate a very useful building block in digital circuits, as it can be used to implement any other logical function.

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In BCD (Binary Coded Decimal) encoding system, 25 will be represented as 00100101. BCD is a system that represents each digit of a decimal number with its equivalent binary code. In BCD, each decimal digit is represented by a four-bit binary code. Therefore, the decimal number 25 is represented in BCD as follows: The binary representation of 2 is 0010, and the binary representation of 5 is 0101. So, combining the binary codes for both digits, we get 0010 0101, which is equivalent to the decimal number 25 in BCD representation. Therefore, the correct option is 00100101.

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The true statements about a computer are: I. Constructed from electronic components: A computer is an electronic device that is constructed using various electronic components such as transistors, capacitors, resistors, etc. III. It has facility for storage of data and programs: A computer has a storage device, such as a hard disk, that allows it to store data and programs for later use. IV. It has provision for input and output of data: A computer has various input devices such as a keyboard and mouse, which allow users to input data, and output devices such as a monitor or printer, which allow users to receive information from the computer. II. It has self-regeneration capability: This statement is not true. While computers are designed to detect and correct errors, they do not have the ability to regenerate or repair themselves without human intervention. Therefore, the statements that are true about computers are I, III, and IV.

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The file organization method that can be accessed both randomly and sequentially is the Indexed Sequential Files. Indexed Sequential Files use an index to organize data records, allowing for both sequential and random access. The records are stored in sequence based on a primary key field, and the index keeps track of the location of each record. This allows for sequential access by reading the records in order, or random access by searching for a specific record based on its key value. For example, imagine a library catalog that is organized using an Indexed Sequential File. The books in the library are stored in order by their call numbers (i.e., the primary key field), and an index is kept that maps each call number to its location in the library. A patron could browse the catalog sequentially by looking at each book in order, or they could search for a specific book by using the index to find its location. Overall, Indexed Sequential Files provide the flexibility of both sequential and random access, making them a popular choice for applications that require both types of access.

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The labeling of hard drives depends on the specific operating system being used. However, it is common for disk operating systems to label hard drives as letters starting from "C". This is because the first two letters, "A" and "B", are reserved for floppy drives. So, the most common labeling of hard drives is "C, D, and E".

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The collection of software that allows a computer to operate is called an Operating System (OS). An Operating System is a software that manages computer hardware and provides common services for computer programs. It acts as an interface between the hardware components of the computer and the applications that run on it. The operating system is responsible for managing resources such as memory, CPU time, and input/output operations. It also provides a user interface that enables users to interact with the computer and run applications. General-purpose software and specific software are not appropriate terms to describe the collection of software that allows a computer to operate. General-purpose software refers to software that can perform a variety of functions, such as word processing, spreadsheet management, and email communication. Specific software, on the other hand, is designed to perform a particular task, such as graphic design or accounting. Utility software, on the other hand, refers to software that performs specific tasks to maintain the performance and functionality of a computer system, such as virus scanners, disk defragmenters, and backup tools. However, utility software alone cannot allow a computer to operate; it needs an operating system to function. Therefore, the collection of software that allows a computer to operate is called an Operating System.

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The effects of file insecurity include virus infection, file corruption, and data loss. However, encrypted data is not an effect of file insecurity. When files are insecure, they can be easily infected by viruses and malware, which can cause harm to the computer and compromise sensitive data. File corruption can occur due to various reasons such as hardware failure, software errors, or virus attacks. This can lead to files becoming unreadable or unusable, which can cause significant inconvenience and loss of important information. Data loss is also a common effect of file insecurity, which can occur due to accidental deletion, system failure, or hardware damage. Encrypted data, on the other hand, is a security measure that is used to protect files and data from unauthorized access. It is not an effect of file insecurity, but rather a way to prevent file insecurity from happening. Encryption involves converting the original data into a code that is unreadable without a specific decryption key. This helps to ensure that sensitive data is kept safe and secure, even if the files themselves are compromised.

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The map of Nigeria is an example of graphic data. Graphic data refers to any visual representation of information or data, such as graphs, charts, diagrams, and maps. In this case, the map of Nigeria is a visual representation of the geographic features and boundaries of the country. It shows the different regions, states, and cities within Nigeria, as well as its neighboring countries and bodies of water. The map uses a combination of colors, symbols, and labels to convey information about Nigeria's geography in a clear and easily understandable way.

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A scanner and a floppy disk are respectively an input device and a storage device. A scanner is a device used to convert a physical document or image into a digital format. It works by using a light source to capture an image and then digitize it. This means that it takes information from the physical world and converts it into a form that a computer can understand and process, making it an input device. On the other hand, a floppy disk is a type of removable storage device used to store and transfer data. It works by using magnetic storage to store data on a disk that can be easily removed and used in another computer. This means that it takes information from the computer and stores it in a physical form that can be accessed later, making it a storage device.

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Spreadsheet packages are software programs that allow users to create, manipulate and analyze data in the form of tables, charts and graphs. They are mainly used for budgeting and inventory management because they offer powerful tools for financial analysis and data organization. With a spreadsheet package, you can create and format tables with columns and rows to track expenses, sales, and other important data. You can also use formulas and functions to automatically calculate totals, averages, and other important metrics. In addition to budgeting and inventory, spreadsheet packages can also be used for a wide range of other tasks, such as analyzing data trends, creating charts and graphs to visualize data, and performing mathematical calculations. Some spreadsheet packages even offer features for collaborating on documents and sharing data with others in real-time. However, spreadsheet packages are not designed for database management, word processing, drawing, or painting. For those tasks, you would need to use other software programs designed specifically for those purposes.

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The input device that converts an image into text is known as an Optical Character Reader (OCR). OCR is a technology that uses specialized software to recognize text characters within an image and then converts them into a digital format that can be edited, searched, and processed like any other text data. OCR technology can be used for a variety of applications such as digitizing printed documents, translating languages, and recognizing handwritten text. In summary, an OCR is a tool that helps to convert an image of printed or handwritten text into digital text that can be easily edited and manipulated.

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The answer is "close symbol." Flowcharts are diagrams that are used to represent the flow of a process or system. They use different symbols to represent different elements of the process, such as starting points, decision points, and actions. Terminal symbols, also known as start/end symbols, are used to indicate the beginning or end of a process or flowchart. Process symbols are used to represent actions or steps in the process, while input/output symbols are used to represent data inputs or outputs. However, there is no such thing as a "close symbol" in flowcharting. There are, however, symbols such as the decision symbol, which is used to indicate a point in the process where a decision needs to be made based on a condition or set of conditions. In summary, the correct answer is "close symbol" because there is no such symbol used in flowcharting.

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The two kinds of sound effect files that can be added to a presentation in Microsoft PowerPoint are .wav files and .mid files. .wav files are audio files that contain sound recordings, such as music or voice recordings. They are widely used for sound effects and background music in presentations. .mid files are musical instrument digital interface files that contain musical notes and instructions for playing them. They are used to add background music or sound effects to a presentation that are specifically composed or synthesized for the presentation.

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Data that is copied from an application is stored in the clipboard. The clipboard is a temporary storage location that allows you to copy and paste information between different applications or within the same application. When you copy data, it is stored in the clipboard, which is a type of memory that holds the data until you paste it elsewhere. Once you paste the data, it is removed from the clipboard, and the clipboard is ready to store new data. Therefore, the clipboard acts as a buffer that allows you to move information from one place to another, making it a useful tool for working with multiple applications or files.

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The cell that contains the pointer or cursor in Microsoft Excel is referred to as the "Active Cell". An active cell is the cell that is selected and ready to accept data or a formula. You can tell which cell is active because its border is highlighted with a different color or pattern. When you start typing, the data will be entered into the active cell.

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Machine language instructions are expressed in binary. Binary is a system of representing numbers using only two digits, 0 and 1. Computers understand and process data in binary form, making it the most basic and fundamental language for computers. Machine language instructions are written using binary code, which the computer can directly execute without any further translation.

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The set of instructions written by computer experts to solve a specific task of the user is called application software. Application software is a type of computer software that is designed to perform specific tasks, such as word processing, spreadsheet management, and media editing. It is created by developers to meet the needs of users, and it is installed onto a computer to help the user perform a certain task. Examples of application software include Microsoft Word, Excel, and Adobe Photoshop. Operating systems, system software, and utility software are different types of software. The operating system is the primary software that manages all of the hardware and software resources of a computer, while system software includes programs that help manage and maintain the computer, such as device drivers, security software, and system utilities. Utility software refers to programs that are designed to perform specific tasks, such as disk cleanup, backup, and optimization.

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Data transfer cannot be initiated through trunking pipe. Trunking pipes are used to protect and route cables, but they are not capable of initiating data transfer themselves. On the other hand, coaxial cable, fibre cable, and twisted pair cable are all examples of media that can be used to initiate data transfer. Coaxial cable uses a central conductor surrounded by insulation and a grounded shield to transmit signals, while fibre cable uses thin strands of glass or plastic to transmit light signals, and twisted pair cable uses pairs of copper wires twisted together to transmit electrical signals. Each of these media has its own advantages and disadvantages, and the choice of which one to use will depend on factors such as distance, bandwidth requirements, and cost.

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To hold row and column titles in place so that they do not scroll when the user scrolls a worksheet in Microsoft Excel, you can use the Freeze Panes command on the Windows menu. This command allows you to select a row or column that you want to keep in place, and then freeze that row or column so that it remains visible when you scroll through the rest of the worksheet. This feature is helpful when you have a large spreadsheet with many rows and columns, and you want to keep the headers or labels in view as you work with the data. The other options listed in the question (Hold Titles, Split, and Show Grid) do not have the same function as Freeze Panes and will not allow you to hold row and column titles in place.

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Modern computers are faster and smaller compared to earlier computers. They can perform many tasks much faster and have more storage capacity for things like music, videos, and photos. They also often come in compact designs that make them more portable. However, it is important to note that technology is constantly evolving, so it's possible for there to be newer computers that are even faster and smaller than current ones.

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The three major types of language translators are: Assembler, Compiler, and Interpreter. An Assembler is a translator that converts assembly language code, which is a low-level programming language, into machine language code that a computer can understand and execute. Assembly language is specific to a particular computer architecture, so an assembler is also specific to that architecture. A Compiler is a translator that converts high-level programming language code, which is more human-readable, into machine language code that a computer can understand and execute. The process of compilation involves several stages, including lexical analysis, syntax analysis, semantic analysis, code generation, and optimization. Once compiled, the resulting machine code can be run repeatedly without needing to recompile the source code. An Interpreter is a translator that works by executing high-level programming language code directly, without the need to first compile it into machine language code. Interpreters translate code line-by-line, executing each line immediately before moving on to the next one. This process is slower than compilation, but it allows for greater flexibility and interactivity during development, as changes to the source code can be tested immediately without needing to recompile.

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The suite of software that controls and manages the basic operation of a computer is called system software. It includes programs that provide essential functionalities like managing hardware resources, running other software applications, and providing a user interface for interacting with the computer. Examples of system software include operating systems like Windows, macOS, and Linux, device drivers, system utilities, and firmware. System software is different from application software, which is designed to perform specific tasks like word processing, spreadsheet management, or video editing.

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(a)

i)Flow chart diagram

ii) Name the parts

(b)

1. (i) The documentation stage in Program Development Life Cycle is the stage where the developer writes down the details of the program including its design, code, and testing procedures. This documentation helps in maintaining and updating the program later.
2. (ii) Three characteristics of a good computer program are:
• 1. User-friendly: The program should be easy to use and understand for the intended audience.
• 2. Efficient: The program should run quickly and efficiently, without taking up too much memory or processing power.
• 3. Reliable: The program should produce accurate and reliable results and should be free of bugs and errors.

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(a)(i) Encryption is the process of converting plain or readable data into a coded or unreadable format using an algorithm. This process helps to secure the confidentiality of sensitive information and prevents unauthorized access or interception of data.

(a)(ii) Two authentication techniques involved in security measure from Table 1 are:

• Biometric: This technique involves verifying a person's identity based on unique physical or behavioral characteristics such as fingerprints, face recognition, or voice recognition.
• Password: This technique involves a secret code or passphrase known only to the user that grants access to a system, application, or data.

(a)(iii) Two features of data encryption are:

• Confidentiality: Encryption provides confidentiality by ensuring that only authorized users can access and read the encrypted data. Even if the data is intercepted, it remains unreadable without the decryption key.
• Integrity: Encryption also provides integrity by ensuring that the data has not been tampered with during transmission or storage. Any changes made to the encrypted data will render the decryption process useless.

(b) Four factors that may be responsible for the delay in data transfer through mobile phone are:

• Network congestion: When many users are accessing the same network simultaneously, it can cause congestion and slow down the data transfer speed.
• Poor signal strength: If the mobile phone has a weak signal or is in an area with poor network coverage, it can affect the data transfer speed.
• Large file size: Large files take longer to transfer than small files, and this can cause a delay in data transfer.
• Processing power: The processing power of the mobile phone can also affect data transfer speed. Older phones or phones with low processing power may take longer to transfer data than newer phones with higher processing power.

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To complete the task outlined in the question, you can follow these steps:

1. Open a spreadsheet application such as Microsoft Excel or Google Sheets.
2. In cell A1, type the text "My One Week Expenses On Five items".
3. In row 2, type the following column headings: "ITEM", "1ST DAY", "2ND DAY", "3RD DAY", "4TH DAY", "5TH DAY", "6TH DAY", "7TH DAY".
4. In column A, starting from A3 to A7, list the items you spent money on.
5. Enter the amount spent on each item for each day in their respective columns.
6. In cells A12 and A8, type "TOTAL".
7. In the cells below the "TOTAL" row, use the SUM formula to calculate the total expenses for each day and for each item. For example, to calculate the total expenses for the first day, you could use the formula "=SUM(B3:B7)".
8. Select the entire table and add borders to it.
9. Insert a footer and type in your full name and index number.
10. Below the table, in cell A18, type the formula that was used to calculate the total expenses for each day. For example, if the formula used was "=SUM(B3:H3)", type "=SUM(B3:H3)" in cell A18.
11. Save your work with your full name as the file name in a folder on the desktop.
12. Print your work and submit it to the supervisor.

This will give you a complete table of your expenses for one week on five items, along with the total expenses for each day and for each item.

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(a)

1. (i) A storage device is a physical device used to store digital information such as data, documents, pictures, videos, or software programs. Storage devices can be classified into primary storage devices and secondary storage devices. Primary storage devices include Random Access Memory (RAM) and cache memory, while secondary storage devices include Hard Disk Drives (HDDs), Solid State Drives (SSDs), USB flash drives, CD/DVDs, and memory cards.

2. (ii) Virtual memory is a technique used by a computer's operating system to expand the available memory by using the hard disk as temporary storage. When a computer runs out of RAM, it moves some of the less frequently used data from RAM to the hard disk, freeing up space in RAM for more immediate data. The operating system manages this process automatically, and the user is generally unaware of it.

(b)

1. (i) 2KB can hold 2,048 bits (1 byte = 8 bits, therefore 2KB = 2,048 bytes x 8 bits/byte = 16,384 bits) while 2MB can hold 16,777,216 bits (2MB = 2,048,000 bytes x 8 bits/byte = 16,777,216 bits).

2. (ii) To calculate the total capacity in bytes when the two storage devices are put together, we simply add the capacities of the two devices. Thus, the total capacity is 2KB + 2MB, which equals 2,048 bytes + 2,048,000 bytes = 2,050,048 bytes.

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(a) (i) A firewall is a security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a private internal network and the public Internet, protecting sensitive data and systems from unauthorized access, hacking attempts, and other security threats.

(ii) Two methods used in protecting computer systems are:

• Antivirus/Antimalware software: Antivirus software is used to detect, prevent, and remove malicious software (malware) such as viruses, worms, and Trojans from infecting a computer system.
• Encryption: Encryption is the process of converting sensitive data into a code to prevent unauthorized access. It helps protect data in transit and at rest.

(b) (i) Feasibility Study: The feasibility study is the first stage of the System Development Life Cycle. It involves evaluating a proposed system to determine whether it is technically, economically, and operationally feasible. This stage helps to identify potential risks and challenges and determine if the proposed system is worth pursuing.

(ii) Design: The design stage involves creating a detailed blueprint of the proposed system, including its architecture, components, and interfaces. This stage also involves defining system requirements and specifications, and determining the methods and technologies to be used in building the system.

(iii) Maintenance: The maintenance stage is the ongoing process of monitoring and updating the system to ensure that it continues to meet its requirements and perform as expected. This may involve fixing bugs and other technical issues, updating software, and making other improvements to the system. It is an important part of the System Development Life Cycle as it helps to maintain the integrity and reliability of the system over time.