WAEC SSCE - Computer Studies - 2016
Ibeere 1 Ìròyìn
The software whose output is intended for the human user is called?
Awọn alaye Idahun
The software whose output is intended for the human user is called "application software". Application software refers to any program or group of programs designed for end-users that perform a specific function. Examples of application software include word processors, spreadsheets, media players, and graphic design software. The main purpose of application software is to provide solutions or services that can be used directly by the end-users to perform various tasks. Unlike system software, which manages and controls computer hardware and provides a platform for running other software applications, application software is developed to address specific needs of the end-users.
Ibeere 2 Ìròyìn
A block of text that is marked by the tab key when the enter key is pressed can be referred to as?
Awọn alaye Idahun
A block of text that is marked by the tab key when the enter key is pressed is referred to as a "paragraph". In word processing, a paragraph is a unit of text consisting of one or more sentences that are separated from other paragraphs by a blank line or indentation. A paragraph usually expresses a single idea or topic and is often used to organize writing into discrete sections. The tab key is commonly used to indent the first line of a paragraph, creating a visual separation between paragraphs and making the text easier to read.
Ibeere 4 Ìròyìn
The smallest unit of information representation which is addressable on the computer memory is?
Awọn alaye Idahun
Ibeere 5 Ìròyìn
Which of the following can be described as the brain of the computer hardware?
Awọn alaye Idahun
Ibeere 6 Ìròyìn
The first four steps required to open e-mail account include:
I click on "Create my account"
II go to home page of the service provider
III click "create new account"
IV click on "mail"
Awọn alaye Idahun
The correct sequence of the first four steps required to open an email account is: II, IV, III and I. First, we need to go to the home page of the email service provider (II) and then click on "mail" (IV) to access the email service. After that, we need to click on "create new account" (III) to start the process of creating a new email account. Finally, we click on "Create my account" (I) to complete the process of setting up a new email account.
Ibeere 7 Ìròyìn
The initial screen that is displayed after a computer booting is referred to as?
Awọn alaye Idahun
The initial screen that is displayed after a computer booting is referred to as the "desktop". It is the primary visual interface that allows users to interact with the computer and access various applications and files. The desktop typically includes icons, folders, and other graphical elements that represent programs or files stored on the computer. It serves as a launching point for applications and provides easy access to system settings and configuration options. The desktop can be customized according to the user's preferences, such as changing the background image or organizing icons in a specific manner.
Ibeere 9 Ìròyìn
The chart type that does not have the X and Y axis display is the?
Awọn alaye Idahun
The chart type that does not have the X and Y axis display is the pie chart. A pie chart is a circular chart that is divided into slices to represent numerical proportions of a whole. The slices in a pie chart do not have axes since they are not measured on a scale. Instead, they represent parts of a whole in relation to each other. The size of each slice is proportional to the quantity it represents, making it easy to visualize the relative sizes of different categories.
Ibeere 10 Ìròyìn
Which generation of computers used vaccum tubes in their circuitry?
Awọn alaye Idahun
The generation of computers that used vacuum tubes in their circuitry is the first generation. Vacuum tubes were used as the primary electronic component for computation and data storage during this era, and were a significant improvement over earlier mechanical computing devices. However, vacuum tubes were large, unreliable, and generated a great deal of heat, which limited the speed and size of these early computers. The first generation of computers lasted from the late 1940s to the mid-1950s, when they were gradually replaced by the second generation, which used smaller and more reliable transistors instead of vacuum tubes.
Ibeere 11 Ìròyìn
Symptoms of computer virus attack include:
I improved processing speeds; Il drive light coming up without a parent reason; Ill unexplainable printer activity; IV the disappearance or strange files appearance on screen
Awọn alaye Idahun
Ibeere 12 Ìròyìn
Which of the following is true about raw data?
Awọn alaye Idahun
Raw data is unprocessed data that has not been organized or analyzed. It can exist in various forms, including written, oral, and digital formats. Raw data may contain errors, duplications, and inconsistencies, and it may be difficult to make sense of the data without further processing. Therefore, raw data is generally not reliable for making decisions without first being analyzed and transformed into meaningful information. So, the correct option is "It cannot be relied on to make a decision."
Ibeere 13 Ìròyìn
Use the BASIC program below to answer questions 23 to 25
10 LET K = 2
20 LET L = 9
30 LET SUM = 0
40 FOR J = K TO STEP 2
50 SUM = SUM + J\(^2\)
60 PRINT "ANSWER =", SUM
70 NEXT J
80 END
How many times will the statement lines 50 and 60 be repeated?
Awọn alaye Idahun
The statement in line 40 sets up a loop that will run from the value of K to a final value (not specified in the program). The "STEP 2" in line 40 indicates that the loop variable J will be incremented by 2 at each iteration. Since K is initialized to 2 in line 10, the loop will start with J = 2. The final value of J is not specified in the program, but we can see that the loop will continue as long as J is less than or equal to L (which is initialized to 9 in line 20). Therefore, the values of J that will be used in the loop are 2, 4, 6, 8. This means that the statements in lines 50 and 60 will be repeated 4 times. So the answer is (C) 4.
Ibeere 14 Ìròyìn
Which of the following is a temporary file that can be used only once and then discarded?
Awọn alaye Idahun
Ibeere 15 Ìròyìn
Software is referred to as the?
Awọn alaye Idahun
Software is the generic term for computer programs, which are sets of instructions that direct a computer to perform specific tasks or operations. It refers to the intangible components of a computer system that provide instructions to the hardware, enabling it to perform various functions. Examples of software include operating systems, application programs, device drivers, and utility programs. Unlike hardware components, software is not physical and cannot be touched or broken.
Ibeere 17 Ìròyìn
Which of the following networks can be extended to cover continents?
Awọn alaye Idahun
The network that can be extended to cover continents is a Wide Area Network (WAN). A WAN is a type of computer network that covers a large geographic area, such as a city, country, or even multiple countries. It typically connects multiple Local Area Networks (LANs) and Metropolitan Area Networks (MANs) across a wide area using various communication technologies such as satellite, leased lines, and fiber optic cables. WANs are commonly used by organizations with multiple locations in different cities or countries to connect their networks together and enable communication and data sharing between them.
Ibeere 19 Ìròyìn
The parts of the taskbar include:
I recycle bin
II start button
III system tray
IV quick launch toolbar
Awọn alaye Idahun
Ibeere 20 Ìròyìn
Which of the following is not a biometric data?
Awọn alaye Idahun
The answer is "password". Biometric data refers to physical or behavioral characteristics that can be used to identify an individual, such as fingerprints, iris patterns, and voice patterns. Passwords, on the other hand, are not physical or behavioral characteristics, but rather a sequence of characters used to authenticate a user's identity. While passwords can be used for security purposes, they are not considered biometric data.
Ibeere 22 Ìròyìn
Which of the following can a traveler who finds himself in a new environment rely on for direction to his final destination?
Awọn alaye Idahun
Ibeere 24 Ìròyìn
A common communication pathway shared by hard- ware components in the computer is called?
Awọn alaye Idahun
The common communication pathway shared by hardware components in a computer is called a "bus". A bus is like a virtual highway that allows different parts of the computer to communicate with each other. Just like cars on a highway, different parts of the computer can send data back and forth on the bus to get things done. For example, the CPU (Central Processing Unit) can send a request for data to the RAM (Random Access Memory) on the bus, and the RAM can send the data back to the CPU on the same bus. There are different types of buses in a computer, such as the data bus, address bus, and control bus. Each type of bus is responsible for different aspects of communication, such as sending data, specifying where the data should go, and controlling the flow of data. Overall, the bus is an essential component of a computer's architecture that enables the different hardware components to work together efficiently and effectively.
Ibeere 25 Ìròyìn
Principal uses of word processing software packages include:
I. preparing deft articles for publication
II. Preparing reports for top management
III. preparing accounts
IV. preparing organizations' newsletter.
Awọn alaye Idahun
Ibeere 26 Ìròyìn
The symbol used to represent an execution flow in a flowchart is?
Awọn alaye Idahun
The symbol used to represent an execution flow in a flowchart is typically an arrow. The arrow usually points from the symbol representing the starting point to the symbol representing the next step in the process or decision-making. The arrow may also include labels indicating the direction of the flow or the nature of the connection between the two symbols.
Ibeere 27 Ìròyìn
In a database, a primary key is a field which contains?
Awọn alaye Idahun
In a database, a primary key is a field which contains unique entries. This means that no two records in the database can have the same value in the primary key field. The purpose of a primary key is to uniquely identify each record in the database and to allow for easy retrieval and manipulation of data. It can be a text, numeric or alphanumeric value, as long as it is unique for each record. Duplicate values are not allowed in a primary key field, as this would make it impossible to distinguish between two or more records.
Ibeere 28 Ìròyìn
The primary memory of the computer can be divided into?
Awọn alaye Idahun
The primary memory of a computer can be divided into two types: random access memory (RAM) and read-only memory (ROM). RAM is a type of volatile memory that allows the computer to read and write data quickly, but loses its data when the computer is turned off. ROM, on the other hand, is non-volatile memory that stores data permanently and cannot be changed or overwritten by the user.
Ibeere 33 Ìròyìn
Identify the browsers in the following list:
I telnet II netscape navigator.ll opera IV mozilla firefox
Awọn alaye Idahun
The browsers in the given list are: - Netscape Navigator - Opera - Mozilla Firefox Therefore, the answer is option (C) II, III and IV only.
Ibeere 34 Ìròyìn
The illegal copying and use of proprietary/copy righted software is called?
Awọn alaye Idahun
The illegal copying and use of proprietary/copyrighted software is called software piracy. It refers to the act of using, copying, distributing, or selling software without proper permission or a valid license. It is a form of intellectual property theft and is illegal in most countries. The practice deprives software developers and companies of their rightful revenue and can lead to the spread of malware and other security risks.
Ibeere 35 Ìròyìn
Which of the following is true of a digital logic gate?
.
Awọn alaye Idahun
The correct statement about a digital logic gate is: "It has at least one or more inputs but only one output." A digital logic gate is an electronic circuit that performs a logical operation on one or more binary inputs and produces a single binary output. The input and output signals are represented by binary digits (bits), which can only take on one of two possible states: 0 (false) or 1 (true). Therefore, a digital logic gate must have at least one input, which is either 0 or 1, and it produces an output based on the logical operation performed on the input(s). Some digital logic gates have more than one input, but they always produce only one output. Therefore, options 1, 2, and 4 are incorrect as they state that the gate has only one output or multiple outputs. is correct as it states that a digital logic gate has at least one input but only one output.
Ibeere 36 Ìròyìn
The word bit refers to?
Awọn alaye Idahun
A bit refers to the smallest unit of digital information that can be stored or processed by a computer. It can have a value of either zero or one, representing the two binary digits used by computers to represent information. Therefore, the correct answer is "the value zero or one".
Ibeere 37 Ìròyìn
Which of the following represents features of a computer?
I. It is constructed from electronics components.
II. It has self regeneration capability.
IlI. It has facility for storage of data and programs.
IV. It has provision for input and output data.
Awọn alaye Idahun
The correct answer is option III - I, III, and IV only. Explanation: - Feature I is correct as computers are constructed from electronic components such as transistors and integrated circuits. - Feature II is incorrect as computers do not have self-regeneration capability. They rely on external sources such as software updates and hardware replacements for repair. - Feature III is correct as computers have facilities for the storage of data and programs in various forms such as hard disks, solid-state drives, and memory chips. - Feature IV is correct as computers have provisions for input and output data through devices such as keyboards, mice, and monitors. Therefore, only features I, III, and IV represent the characteristics of a computer.
Ibeere 38 Ìròyìn
Which of the following is not a computer output device?
Awọn alaye Idahun
A computer output device is a hardware component that receives data from a computer and displays or prints the data. It allows the computer to communicate with the user or other devices. A disk is not an output device, it is a storage device. It is used to store data and programs in a computer system. Therefore, the answer to the question is "Disk."
Ibeere 39 Ìròyìn
The speed of data transfer in the computer can be determined in terms of ?
Awọn alaye Idahun
The speed of data transfer in a computer can be determined by two factors: bus speed and bus width. The bus speed refers to how fast data can travel between the components of a computer, such as the processor, memory, and storage devices. The faster the bus speed, the faster data can be transferred between these components. The bus width refers to the number of wires or "lanes" on the bus that are used to transfer data. The wider the bus, the more data can be transferred at once, which can result in faster data transfer rates. Therefore, the speed of data transfer in a computer is determined by both the bus speed and the bus width, as they work together to enable fast and efficient communication between the computer's components. Other factors such as storage media and protocols can also affect data transfer speed, but they are not as directly related to bus speed and bus width.
Ibeere 41 Ìròyìn
Sorting of records is sufficient and a necessary condition for creating?
Awọn alaye Idahun
Sorting of records is a necessary but not a sufficient condition for creating an indexed sequential file. An indexed sequential file is a file organization that combines the features of both sequential and indexed files. Records in an indexed sequential file are stored in a sequential order based on the primary key, but an index is created to allow direct access to the records. Sorting the records is necessary to ensure that they are stored in sequential order based on the primary key. However, creating an index is also necessary to allow direct access to the records using the primary key. Therefore, while sorting is necessary, it is not sufficient on its own to create an indexed sequential file.
Ibeere 42 Ìròyìn
Which of the following was used by Joseph Marie Jacquad in inventing the Loom?
Awọn alaye Idahun
Ibeere 43 Ìròyìn
The two main components of a radio communication system are?
Awọn alaye Idahun
The two main components of a radio communication system are the transmitter and receiver. The transmitter is responsible for encoding the information to be transmitted into a signal that can be sent through the airwaves, while the receiver is responsible for receiving the signal and decoding it back into the original information. In other words, the transmitter is the source of the signal, and the receiver is the destination of the signal. The other options listed do not accurately describe the two main components of a radio communication system.
Ibeere 45 Ìròyìn
The first calculating device is the?
Awọn alaye Idahun
The first calculating device is the Abacus. The Abacus is an ancient counting device that was used for mathematical operations such as addition, subtraction, multiplication, and division. It consists of beads or stones that can slide up and down on rods or wires, which are set in a frame. The abacus is still in use today, especially in Asia and Africa, and is often used by merchants, traders, and clerks to perform quick calculations.
Ibeere 46 Ìròyìn
10 LET K = 2
20 LET L = 9
30 LET SUM = 0
40 FOR J = K TO STEP 2
50 SUM = SUM + \(J^2\)
60 PRINT "ANSWER =", SUM
70 NEXT J
80 END
Which of the following best represents the sequence of output from the program?
Which of the following best represents the sequence of output from the program?
Awọn alaye Idahun
The program is adding 2 to the square of each even number from 2 to 8 and printing the result. The even numbers from 2 to 8 are 2, 4, 6, and 8. The square of each of these numbers are 4, 16, 36, and 64 respectively. Adding 2 to each of these squares gives 6, 18, 38, and 66. Therefore, the program will output: 4, 18, 38, 66. The option that best represents this sequence of output is: 4, 20, 56, 120.
Ibeere 47 Ìròyìn
Data to be processed by the microprocessor is temporarily stored in the?
Awọn alaye Idahun
Ibeere 48 Ìròyìn
. Trap doors and bombs are typical examples of?
Awọn alaye Idahun
Trap doors and bombs are typical examples of Trojan horses. A Trojan horse is a type of malware that is disguised as legitimate software but is actually designed to damage or disrupt computer systems, steal information or allow unauthorized access to a computer system. Trap doors and bombs are specifically designed to create vulnerabilities in a computer system that can be exploited by attackers for malicious purposes.
Ibeere 49 Ìròyìn
Arrange in a hierarchical order by date, the following inventions: I. slide rule; Il. pascaline; IIl, analytical engine; v. difference engine.
Awọn alaye Idahun
The correct hierarchical order by date of the given inventions is: II. Pascaline (1642), I. Slide rule (1620s), V. Difference engine (1822), III. Analytical engine (1837-1871). - Pascaline, invented by Blaise Pascal in 1642, was the first mechanical calculator and is the earliest invention in the list. - Slide rule, invented by William Oughtred in the 1620s, is the next in the hierarchy. - Difference engine, invented by Charles Babbage in 1822, is next in the hierarchy. - Analytical engine, also invented by Charles Babbage, was designed between 1837 and 1871 and is the latest invention in the list. Therefore, the correct answer is: I, II, V, III.
Ibeere 50 Ìròyìn
(a) (i) What is a network cable?
(ii) State three types of cable used in networking
(b) Write the acronym VSAT in full.
(C) (i) Distinguish between an e-mail address and a website address.
(ii) List examples of each of: (1) e-mail address (2) website address
(a)(i) What is a network cable?
A network cable is a physical transmission medium (a wire or fibre) used to connect two or more computers or network devices together so that data signals can pass between them.
(a)(ii) Three types of cable used in networking
- Twisted-pair cable (for example UTP/STP, used with RJ-45 connectors).
- Coaxial cable.
- Fibre-optic cable.
(b) VSAT in full
VSAT means Very Small Aperture Terminal.
(c)(i) Difference between an e-mail address and a website address
An e-mail address is the unique identifier of an electronic mailbox to which messages are sent; it always contains the @ symbol in the form username@domain. A website address (URL) is the unique location of a web page or site on the Internet that you type into a browser to view the site; it has no @ symbol and usually begins with a protocol such as http:// or www.
(c)(ii) Examples of each
- E-mail address: ada@yahoo.com; info@waec.org.ng
- Website address: www.waecnigeria.org; https://www.google.com
Awọn alaye Idahun
(a)(i) What is a network cable?
A network cable is a physical transmission medium (a wire or fibre) used to connect two or more computers or network devices together so that data signals can pass between them.
(a)(ii) Three types of cable used in networking
- Twisted-pair cable (for example UTP/STP, used with RJ-45 connectors).
- Coaxial cable.
- Fibre-optic cable.
(b) VSAT in full
VSAT means Very Small Aperture Terminal.
(c)(i) Difference between an e-mail address and a website address
An e-mail address is the unique identifier of an electronic mailbox to which messages are sent; it always contains the @ symbol in the form username@domain. A website address (URL) is the unique location of a web page or site on the Internet that you type into a browser to view the site; it has no @ symbol and usually begins with a protocol such as http:// or www.
(c)(ii) Examples of each
- E-mail address: ada@yahoo.com; info@waec.org.ng
- Website address: www.waecnigeria.org; https://www.google.com
Ibeere 51 Ìròyìn
(a) An electronic book is made up of 500 pages and there are 16 lines of 24,000 bits line on each page.
Complete the space it will occupy on a computer in megabytes.
(b) Give an example of auxiliary storage.
(c) In the table below:
(i) List the two main types of computer software.
(ii) Give two examples under each in 4(c)i)
| main type | example |
| i | A |
| B | |
| ii | A B |
(a) Space occupied by the electronic book.
Given: 500 pages; 16 lines per page; 24,000 bits per line.
Step 1 - total number of bits:
\[ \text{Total bits} = 500 \times 16 \times 24000 = 192{,}000{,}000 \text{ bits} \]
Step 2 - convert bits to bytes (8 bits = 1 byte):
\[ \text{Bytes} = \dfrac{192{,}000{,}000}{8} = 24{,}000{,}000 \text{ bytes} \]
Step 3 - convert bytes to megabytes:
Using \(1\,\text{MB} = 1{,}000{,}000\) bytes:
\[ \dfrac{24{,}000{,}000}{1{,}000{,}000} = 24 \text{ MB} \]
The book therefore occupies about 24 MB. (If the binary convention \(1\,\text{MB} = 1{,}048{,}576\) bytes is used instead, the answer is \(24{,}000{,}000 \div 1{,}048{,}576 \approx 22.89\,\text{MB}\).)
(b) An example of auxiliary (secondary) storage: hard disk drive (also acceptable: flash/USB drive, CD-ROM, DVD, or magnetic tape).
(c) The two main types of computer software with examples:
| Main type | Examples |
|---|---|
| (i) System software | A - Operating system (e.g. Windows) B - Utility program / device driver |
| (ii) Application software | A - Word processor (e.g. Microsoft Word) B - Spreadsheet (e.g. Microsoft Excel) |
Awọn alaye Idahun
(a) Space occupied by the electronic book.
Given: 500 pages; 16 lines per page; 24,000 bits per line.
Step 1 - total number of bits:
\[ \text{Total bits} = 500 \times 16 \times 24000 = 192{,}000{,}000 \text{ bits} \]
Step 2 - convert bits to bytes (8 bits = 1 byte):
\[ \text{Bytes} = \dfrac{192{,}000{,}000}{8} = 24{,}000{,}000 \text{ bytes} \]
Step 3 - convert bytes to megabytes:
Using \(1\,\text{MB} = 1{,}000{,}000\) bytes:
\[ \dfrac{24{,}000{,}000}{1{,}000{,}000} = 24 \text{ MB} \]
The book therefore occupies about 24 MB. (If the binary convention \(1\,\text{MB} = 1{,}048{,}576\) bytes is used instead, the answer is \(24{,}000{,}000 \div 1{,}048{,}576 \approx 22.89\,\text{MB}\).)
(b) An example of auxiliary (secondary) storage: hard disk drive (also acceptable: flash/USB drive, CD-ROM, DVD, or magnetic tape).
(c) The two main types of computer software with examples:
| Main type | Examples |
|---|---|
| (i) System software | A - Operating system (e.g. Windows) B - Utility program / device driver |
| (ii) Application software | A - Word processor (e.g. Microsoft Word) B - Spreadsheet (e.g. Microsoft Excel) |
Ibeere 52 Ìròyìn
(a) State two BASIC programming keywords.
(b) Write the following equations in BASIC format:
(i) I = PRT/100: (ii) Y= AX\(_2\) +BX+C; (iii) Y= MX + C
(c) Write a BASIC program that accepts mass and volume of a liquid as input from the User.
The program should compute.and display the density of the liquid. Density = mass volume
Ibeere 53 Ìròyìn
(a) (i) Define computer virus.
(i) List three types of computer network security breach.
(b) State five sources of computer network security breach.
Awọn alaye Idahun
None
Ibeere 54 Ìròyìn
(a) Convert the following numbers to be stated bases:
(i) 125.625, to binary
(ii) 111011.10011, to octal
(b) Given that X = 11011011 and Y= 11101101,
(i) construct the truth table for X, Y Z;
(ii) draw the logic gate of X, Y = Z
(iii) state the value of Z.
(a) Number-base conversions
(i) Convert \(125.625_{10}\) to base 2.
For the integer part, successive division by 2 gives:
| Division | Quotient | Remainder |
|---|---|---|
| 125 ÷ 2 | 62 | 1 |
| 62 ÷ 2 | 31 | 0 |
| 31 ÷ 2 | 15 | 1 |
| 15 ÷ 2 | 7 | 1 |
| 7 ÷ 2 | 3 | 1 |
| 3 ÷ 2 | 1 | 1 |
| 1 ÷ 2 | 0 | 1 |
Reading the remainders from bottom to top gives \(125_{10}=1111101_2\).
For the fractional part:
\(0.625\times2=1.25\), giving 1;
\(0.25\times2=0.5\), giving 0;
\(0.5\times2=1.0\), giving 1.
Therefore, \(0.625_{10}=0.101_2\), and hence
\[\boxed{125.625_{10}=1111101.101_2}\]
(ii) Convert \(111011.10011_2\) to base 8. Group the binary digits in threes from the binary point:
\[111\;011.100\;110_2=73.46_8\]
\[\boxed{111011.10011_2=73.46_8}\]
(b) \(X=11011011\), \(Y=11101101\), and \(Z=X\mathbin{\text{ AND }}Y\).
(i) Truth table for the AND operation
| X | Y | Z = X AND Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
(ii) Logic-gate diagram
(iii) Value of \(Z\)
| Bit position | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| X | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
| Y | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 |
| Z | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 |
\[\boxed{Z=11001001_2}\]
Awọn alaye Idahun
(a) Number-base conversions
(i) Convert \(125.625_{10}\) to base 2.
For the integer part, successive division by 2 gives:
| Division | Quotient | Remainder |
|---|---|---|
| 125 ÷ 2 | 62 | 1 |
| 62 ÷ 2 | 31 | 0 |
| 31 ÷ 2 | 15 | 1 |
| 15 ÷ 2 | 7 | 1 |
| 7 ÷ 2 | 3 | 1 |
| 3 ÷ 2 | 1 | 1 |
| 1 ÷ 2 | 0 | 1 |
Reading the remainders from bottom to top gives \(125_{10}=1111101_2\).
For the fractional part:
\(0.625\times2=1.25\), giving 1;
\(0.25\times2=0.5\), giving 0;
\(0.5\times2=1.0\), giving 1.
Therefore, \(0.625_{10}=0.101_2\), and hence
\[\boxed{125.625_{10}=1111101.101_2}\]
(ii) Convert \(111011.10011_2\) to base 8. Group the binary digits in threes from the binary point:
\[111\;011.100\;110_2=73.46_8\]
\[\boxed{111011.10011_2=73.46_8}\]
(b) \(X=11011011\), \(Y=11101101\), and \(Z=X\mathbin{\text{ AND }}Y\).
(i) Truth table for the AND operation
| X | Y | Z = X AND Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
(ii) Logic-gate diagram
(iii) Value of \(Z\)
| Bit position | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| X | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
| Y | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 |
| Z | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 |
\[\boxed{Z=11001001_2}\]
