Skip to content

Assignment 2

Corresponds to: Session 2

Questions

1. Given three lists a = [1, 2, 3], b = a and c = a[:], which of the following logical expresions are True? Explain why the results are what they are. A. a == b
B. a is b
C. a == c
D. a is c

Answer

A. a == b -> True. Both the lists a and b contain the same elements.
B. a is b -> True.List object b refers to the same list object as a, so they share the same memory address.
C. a == c -> True. List c is an element-wise copy of the list a, and both contain the same elements.
D. a is c -> False. List c is a new object created by slicing, so it has a different memory address.

2. A quadratic equation is repesented as \(a x^2 + bx + c = 0\), where \(a \neq 0\). The roots are real numbers if \(b^2 - 4 ac \geq 0\). Given the coefficients a, b and c, write the logical expression to check that they represent a quadratic equation with real roots. Note: You must check for the conditions that \(a \neq 0\) and also \(b^2 - 4 ac \geq 0\).

Answer 
if (a != 0) and (b*b - 4*a*c >= 0)

3. Why is it important to design a program before implementing it as code?

Answer
  1. It provides confidence that the final program meets the requirements defined at the start.
  2. It reduces time spent during implementation by clarifying structure and decisions early.

4. When designing a program using the procedural paradigm, how do you decide when to stop sub-dividing a task?

Answer

One useful guideline is to stop sub‑dividing a task when one of the following conditions is met:

  1. The task cannot be divided further.
  2. The task is simple enough that further division is not worthwhile.

5. The two important components of a program are the data (the information required to repesent the problem being solved) and the algorithm (the procedure used to transform the input data to the required output data). What is the primary focus of the procedural paradigm - data or algorithm? Justify your answer.

Answer

The procedural paradigm primarily focuses on the procedure required to accomplish the task. Functions form the core of this paradigm, and programs are built as hierarchies of functions. More abstract, higher‑level functions call simpler, lower‑level functions. Data flows through these functions and is transformed step by step until the desired output is produced. The emphasis is on designing clear, well‑structured procedures, while data is shaped and refined as it moves through the sequence of operations.

Quiz

1. What does the function id(x) return?

A. The data type of x
B. The memory address (identity) of x
C. The size of x in bytes
D. The value x

Answer

Correct answer: B

A. The data type of x is returned by type(x)
B. The memory address (identity) of x
C. The size of x is returned by the function getsizeof() from the built-in module sys. 

>>> import sys
>>> x = 10
>>> sys.getsizeof(x)
28

D. The value of x is returned by using its name x in a statement

2. Which operator checks whether two variables refer to the same object?

A. !=
B. is
C. ==
D. in

Answer

Correct answer: B

A. != checks if a value is not equal to another value
B. is checks if one object has the same identity (memory address) as another object
C. == checks if one value is equal to another value
D. in checks if one value is contained in a given container object

3. If a = [1, 2] and b = [1, 2], what is the result of a == b?

A. Depends on Python version
B. True
C. Error
D False

Answer

Correct answer: B

A. The answer is the same in all versions of Python
B. True -> Both objects have the same values. Note: 1 == 1.0 where the first value is an int and the second is a float
C. No error is reported when comparing a == b
D. Not false -> Both a and b have the same values

4. If a = [1, 2] and b = [1, 2], what is the result of a is b?

A. False
B. Error
C. True
D. Depends on indentation

Answer

Correct answer: C

A. Even though they both have the same values, they have different identities (memory address)
B. Not an error. a is b is not an error, it is a valid statement
C. Not true -> They do not have the same identity, therefore not True
D. Does not depend on indentation

5. Which logical operator returns True only if both conditions are true?

A. xor
B. and
C. not
D. or

Answer

Correct answer: B

6. What is the result of True or False?

A. False
B. Error
C. True
D. None

Answer

Correct answer: C

An or condition is True if one of the two operands is True. It is False only when both are False.

7. What does the not operator do?

A. Checks identity
B. Reverses a bool value
C. Creates a new variable
D. Compares two values

Answer

Correct answer: B

The not operator inverts the value of a bool value. Thus not True return False and not False returns True.

8. Which of the following is a valid logical expression?

A. 5 multiply 10
B. 5 equals 10
C. 5 plus 10
D. 5 and 10

Answer

Correct answer: D

None among multiply, equals and plus is a valid Python operator. 5 and 10 returns 10, the second operator. This is how Python logical and expressions are evaluated:

  1. If the left operand is falsy (0, "", None, False or []) the logical expression returns the first operand, without evaluating the second operand. In this example, the first operand 5 is not False.
  2. If the left operand is not falsy, the expression returns the second operand, which in this example is 10..

Thus 5 and 20 will return 20 and 5 and False will return False and 0 and 10 will return 0.

9. In VS Code, where do you typically see error messages and program output?

A. The Activity bar
B. The Explorer panel
C. The Extension panel
D. The Terminal panel

Answer

Correct answer: D

The Terminal panel lets the user type commands and display results of executing programs

10. Which VS Code panel shows your files and folders?

A. Extension B. Source Control C. Explorer D. Run and Debug

Answer

Correct answer: C

The Explorer lets the user navigate the filesystem with the directory open in VS Code as the root dirctory. User can traverse downward from this root but not upwards.

11. What is the purpose of the VS Code Command Palette?

A. To display errors B. To manage Git branches C. To run commands quickly D. To store code snippets

Answer

Correct answer: C

The Command Palette is VS Code’s universal command launcher. Instead of hunting through menus, you can open it and fuzzy‑search for any action VS Code can perform — built‑in commands, extension commands, settings, navigation tools, and more.

12. True or False: The is operator checks whether two objects have equal values.

A. False B. True C. Sometimes True D. Only for integers

Answer

Correct answer: A

The is operator check whether two objects have the same identity (memory address) not whether they have equal values.

13. Which logical operator would make this expression True: False ___ True?

A. and B. not C. is D. or

Answer

Correct answer: D

A. and -> False and True is False
B. not -> False not True is an error
C. is -> False is True is False because they have different identities (memory address)
D. or -> False or True is True as the left operand is True

14. If a = 5 and b = 10, c = -3 and d = a, what are the results of the following logical operations?

A. 0 <= c <= a
B. c <= a <= b
C. a != c
D. not (a >= c)
E. a is d
F. c is not d

Answer

A. 0 <= c <= a -> False because this is equivalent to (0 <= -3) and (c <= 5) and 0 <= -3 is False and one False results in the and expression to evaluate to False
B. c <= a <= b -> True because (-3 <= 5) and (5 <= 10 is True
C. a != c -> True because 5 != -3 is True
D. not (a >= c) -> True because 5 >= -3 is True
E. a is d -> True because in Python they both have the same memory address, which is the memory address of the immutable integer value 5
F. c is not d -> True because c and d are integers with different vlues and therefore have different memory addresses. Thus c and d do not have the same memory address, which is true.