Software Engineering 2080 paper solutions

 

1. What is Software Engineering? Differentiate between Program and Software. Explain Generic and Customized Software.

What is Software Engineering? (2 Marks)

Software Engineering is a systematic and disciplined approach to designing, developing, testing, and maintaining software. It applies engineering principles to software development to ensure that software is reliable, efficient, scalable, and cost-effective.

Why is Software Engineering Important?

1. Reduces Complexity: Large software projects are divided into smaller modules, making them easier to develop.
2. Improves Quality: Follows structured processes like SDLC, Agile, or DevOps.
3. Ensures Reliability: Software is tested thoroughly to minimize failures.
4. Cost-Effective: Reduces errors and unnecessary rework, saving time and money.
5. Easy Maintenance: Well-documented code helps future developers modify the software easily.

Difference Between Program and Software (4 Marks)

Feature	Program	Software
Definition	A set of instructions that performs a specific task	A collection of programs that perform multiple tasks
Size	Small and focuses on a single function	Large and consists of multiple interconnected modules
Development Time	Short, developed by a single person	Long, requires a team of developers
Maintenance	Not required	Regular updates and bug fixes are needed
User Interface	Minimal or none	User-friendly with a GUI
Example	A simple calculator program	Microsoft Office, Adobe Photoshop

 

 Generic and Customized Software (4 Marks)

1. Generic Software

• Developed for a wide range of users with common needs.
• Features are predefined and fixed; cannot be modified for a specific customer.
• Sold in the market for public use.
• Examples:
• Microsoft Office – Used by students, businesses, and professionals.
• Google Chrome – A web browser used worldwide.
• Adobe Photoshop – Graphic designing tool.

2. Customized Software

• Designed specifically for an organization or individual.
• Features are tailored as per customer needs.
• Used by limited users for a specific purpose.
• Examples:
• Banking Software – Developed for a particular bank.
• Hospital Management System – Custom-made for hospitals.
• E-commerce Websites – Amazon, Flipkart, etc.

2. Explain the Steps in SDLC. Write about the Agile Model in Detail.

Software Development Life Cycle (SDLC) (5 Marks)

The Software Development Life Cycle (SDLC) is a step-by-step process used to develop high-quality software. It ensures that software is built in a structured and organized manner.

Steps of SDLC:

1. Requirement Analysis

   • Gather requirements from clients and users.
   • Identify software objectives, constraints, and user needs.
   • Example: A bank wants a mobile app to check account balance.

2. Planning

   • Create a project plan, estimate budget, and assign tasks.
   • Decide technologies and development tools.
   • Example: Using Java for an Android app.

3. Design

   • Design system architecture, database, and user interface (UI).
   • Create flowcharts and wireframes.
   • Example: Designing the login screen for an app.

4. Implementation (Coding)

   • Developers write source code using programming languages.
   • The code is reviewed and optimized.
   • Example: Writing Python code for a chatbot.

5. Testing

   • Identify and fix bugs before launching the software.
   • Perform unit testing, integration testing, and system testing.
   • Example: Checking if a payment gateway works properly.

6. Deployment

   • Release the software for users.
   • Deploy on servers, app stores, or websites.
   • Example: Publishing an app on Google Play Store.

7. Maintenance and Updates

• Fix issues, release updates, and add new features.
• Example: Regular updates for WhatsApp.

Agile Model (5 Marks)

The Agile Model is a flexible and iterative approach to software development. Instead of developing the entire software in one go, it is built in small parts (iterations or sprints).

Key Principles of Agile:

1. Customer Collaboration: Users give feedback after each iteration.
2. Frequent Releases: Software is delivered in small working modules.
3. Flexibility: Easily adapts to changes in user requirements.
4. Teamwork: Developers and users work closely throughout the process.

Steps in Agile Development:

1. Define Requirements – Understand user needs.
2. Plan Sprint – Decide what features to develop.
3. Develop & Test – Write code, test, and fix bugs.
4. Get Feedback – Users review and suggest changes.
5. Improve & Repeat – Implement changes and continue the cycle.

3. What is Software Requirement Engineering? Explain Functional and Non-Functional Requirements.

What is Software Requirement Engineering? (4 Marks)

Software Requirement Engineering (SRE) is the process of gathering, analyzing, documenting, and managing software requirements. It ensures that software meets customer expectations and business needs.

Steps of Requirement Engineering:

1. Requirement Elicitation – Collecting requirements from users.
2. Requirement Analysis – Checking feasibility and conflicts.
3. Requirement Documentation – Writing requirements in reports.
4. Requirement Validation – Confirming correctness.

 

Functional and Non-Functional Requirements (6 Marks)

Feature	Functional Requirement	Non-Functional Requirement
Definition	Defines what the software must do	Defines quality and performance
Purpose	Describes features and behavior	Describes usability and security
Examples	Login system, payment gateway	Speed, scalability, security
Importance	Essential for functionality	Improves user experience

 

4: Cost Estimation and the COCOMO Model

1. What is Cost Estimation?

Cost estimation in software engineering is the process of predicting the total cost required to develop a software project. It helps in planning and budgeting, ensuring that enough resources are available to complete the project successfully.

Why is Cost Estimation Important?

• Helps in proper budget allocation
• Avoids overspending and financial risks
• Supports decision-making in project planning
• Ensures the project is completed within the given resources

Factors Affecting Cost Estimation:

• Project size – Larger projects require more resources and time.
• Complexity – More complex software requires more effort and expertise.
• Team expertise – Skilled teams may complete the project faster, reducing costs.
• Technology used – Different tools and programming languages have different costs.
• Development methodology – Agile, Waterfall, or Hybrid approaches can impact costs.

 

2. The COCOMO Model (Constructive Cost Model)

COCOMO is a widely used cost estimation model developed by Barry Boehm. It helps in estimating the effort, cost, and time required to develop a software project based on its size and complexity.

Types of COCOMO Models:

COCOMO has three different models based on the complexity of the project:

1. Basic COCOMO Model
• Provides a rough estimate based on the number of lines of code (LOC).
• Uses mathematical formulas to predict effort and cost.
2. Intermediate COCOMO Model
• Considers additional factors like software reliability, database size, and team experience.
• Gives a more accurate estimate compared to the basic model.
3. Detailed COCOMO Model
• Provides the most accurate cost estimation.
• Analyzes different components of the software separately and estimates effort and cost for each.

5: Explain about different Strategies of Software Design

Software design is the process of planning and creating the structure of a software system before coding begins. Different design strategies help in developing efficient, maintainable, and scalable software.

What are Software Design Strategies?

Software design strategies are methods used to organize and develop software systematically. These strategies help in breaking down complex problems into manageable parts, making it easier to build and maintain software.

✅ Why are Design Strategies Important?

• Ensure software is structured and organized
• Make development faster and more efficient
• Improve maintainability and scalability
• Reduce errors and bugs in the system

Types of Software Design Strategies

A. Top-Down Design (Stepwise Refinement)

• Starts from the highest level (big picture) and breaks it down into smaller parts.
• Each module is further divided until it becomes simple enough to be implemented.
• Best for: Large and complex systems.

B. Bottom-Up Design

• Starts by designing the smallest components first and then combines them to form a larger system.
• Focuses on building reusable modules.
• Best for: Projects with well-defined, reusable components.

C. Modular Design

• Divides the software into independent modules, each responsible for a specific function.
• Modules interact with each other but work independently.
• Best for: Large teams working on different parts of a project.

D. Object-Oriented Design (OOD)

• Uses objects (real-world entities) to design software.
• Objects contain data (attributes) and functions (methods) to interact with each other.
• Best for: Modern applications like web apps and mobile apps.

 

E. Prototype-Based Design

• A prototype (early version) of the software is created first.
• Users give feedback, and changes are made before finalizing the design.
• Best for: Projects where requirements are unclear or frequently changing.

6. What is token count? Calculate the length and volume of the following block of program:"

Given Code Block:

int a;
int b;
int c;

if (a > b) and (a > c)
{
    print a;
}
else if (b > a) and (b > c)
{
    print b;
}
else
{
    print c;
}


What is Token Count?
Token count refers to the total number of operators and operands in a program.
Operators: Symbols that perform operations
     (e.g., +,-,*,/,if, else,{}, ;)
 
Operands: Variables, constants, function
     names, and identifiers (e.g., a, b, c, 10)
By counting these tokens, we can calculate a program’s length and volume, which help estimate its complexity
from given program.
 Identifying Operators
Operators are symbols that define operations
in the program.


 

  

   

   
Operators
   
   

   
Count
   
  
 
 

  

  
int (declaration)
  
  

  
3
  
 
 

  

  
; (statement terminator)
  
  

  
3
  
 
 

  

  
if (conditional)
  
  

  
1
  
 
 

  

  
> (comparison)
  
  

  
4
  
 
 

  

  
and (logical operator)
  
  

  
2
  
 
 

  

  
{} (block delimiters)
  
  

  
3 pairs (6)
  
 
 

  

  
else if (conditional)
  
  

  
1
  
 
 

  

  
else (conditional)
  
  

  
1
  
 
 

  

  
print (function)
  
  

  
3
  
 

Total
number of unique operators (n1) = 9

Total occurrences of operators (N1) = 24
Identifying Operands
Operands are variables and constants used in
the program.


 

  

   

   
Operands
   
   

   
Count
   
  
 
 

  

  
a (variable)
  
  

  
4
  
 
 

  

  
b (variable)
  
  

  
4
  
 
 

  

  
c (variable)
  
  

  
3
  
 

Total
number of unique operands (n2) = 3

Total occurrences of operands (N2) = 11
 Calculating Length and Volume
A. Program Length (N)
N = N1 + N2
N=24 + 11 = 35
B. Program Vocabulary (n)
n = n1 + n2
n = 9 + 3 = 12
C. Program Volume (V)
V=N×log2(n)V= 35 x log2(12)
Approximating log₂(12) ≈ 3.58, we get:
$$$$V=35×3.58=125.3
7."What is software Reliability? Explain about the Capability Maturity Model (CMM)" 
What is Software Reliability?
 Definition:
Software reliability refers to the ability of a software system to perform its
required functions without failure
for a specified period under given conditions.
 Why is Reliability Important?
Ensures:  consistent performance
Reduces:  errors and crashes
Improves: user trust and satisfaction
Saves:   maintenance and repair costs
Factors Affecting Software Reliability:

Faults in Code – Bugs and errors reduce reliability.
External Conditions –Hardware issues, network problems, or environmental factors can affect
     performance.
Usage Intensity – More users or high processing demands may lead to failures.
Software Complexity – A complex system is harder to test and maintain, reducing reliability.

Measuring Software Reliability
There are three common ways to measure
software reliability:


 

  

   

   
Metric
   
   

   
Explanation
   
  
 
 

  

  
MTBF (Mean Time
  Between Failures)
  
  

  
Measures
  the average time a system works before failing. A higher MTBF means better
  reliability.
  
 
 

  

  
MTTR (Mean Time to
  Repair)
  
  

  
Measures
  the average time required to fix a failure. A lower MTTR means faster
  recovery.
  
 
 

  

  
Failure Rate
  
  

  
Measures
  how often the software fails in a given period. Lower failure rates mean
  better reliability.
  
 
 Capability
Maturity Model (CMM)
The Capability
Maturity Model (CMM) is a framework that helps organizations improve
software quality and reliability. It consists of five levels that represent the maturity of an organization’s
software development process.
 Why is CMM Important?
Improves   software quality and reliability
Provides  a structured approach to  development
Reduces  bugs and failures
Increases  customer satisfaction

Five Levels of CMM

 

  

   

   
Level
   
   

   
Description
   
  
 
 

  

  
1. Initial (Chaotic
  Stage)
  
  

  
No
  formal process; development is unorganized.
  
 
 

  

  
2. Repeatable
  (Managed Stage)
  
  

  
Basic
  project management and tracking are introduced.
  
 
 

  

  
3. Defined
  (Standardized Stage)
  
  

  
Development
  processes are well-defined and documented.
  
 
 

  

  
4. Managed (Measured
  Stage)
  
  

  
Quantitative
  tracking of software quality and performance.
  
 
 

  

  
5. Optimized
  (Continuous Improvement)
  
  

  
Continuous
  improvement using new technologies and feedback.
  
 



8: What is Testing, Explain Black Box Testing, and White Box
Testing
What is Software Testing?
 Definition:

Software testing is the process of checking whether a software program works correctly and is free of errors before being used by
customers.
Why is Testing Important?
 
Ensures the software functions properly.

 
Detects and fixes bugs before release.

 
Improves user experience and software reliability.

Types of Software Testing
Software testing is mainly divided into:
 
Black Box Testing (Focuses on input and output)

 
White Box Testing (Focuses on internal code
     and logic)
 Black Box Testing (4 Marks)
 Definition: 
Black Box Testing tests the software without
     looking at the internal code.
 
The tester checks only the inputs and outputs
     to see if the program behaves correctly.
 Key Features: 
The tester does not need coding knowledge.
 
Focuses on what the software does,
     not how it works.
 
Used for functional testing
     (checking features like login, buttons, calculations, etc.).
 Advantages:

✔ Easy to perform.

✔ Works well for large applications.

✔ Detects missing or incorrect functions.
 Disadvantages:

❌ Does not check internal coding errors.

❌ Cannot test all possible inputs.
 White Box Testing (4 Marks)
Definition: 
White Box Testing checks the internal
     structure, logic, and code of a software program.

 
The tester needs programming knowledge to
     examine how the code executes.
 Key Features: 
Focuses on how the software works internally.

 
Used for unit testing (testing
     individual functions or code blocks).

 
Helps find hidden bugs in code logic.
Advantages:

✔ Identifies logical errors in code.

✔ Ensures each function works as expected.

✔ Finds security vulnerabilities.
Disadvantages:

❌ Requires coding knowledge.

❌ Cannot test the overall software usability.
 Key Differences: Black Box vs. White Box
Testing

 

  

   

   
Feature
   
   

   
Black Box
   Testing
   
   

   
White Box
   Testing
   
  
 
 

  

  
Focus
  
  

  
Functionality (What the software does)
  
  

  
Internal Code (How the software works)
  
 
 

  

  
Tester’s Knowledge
  
  

  
No coding knowledge needed
  
  

  
Requires programming skills
  
 
 

  

  
Example
  
  

  
Testing a login form
  
  

  
Checking password encryption code
  
 
 

  

  
Use Case
  
  

  
User Interface, Forms, Buttons
  
  

  
Logic, Security, Algorithms