[Python-Institute] Python-Institute - PCEP-30-02 Exam Dumps & Study Guide

Free [Python-Institute] Python-Institute - PCEP-30-02 Practice Questions Preview

• Question 1

  Insert the correct snippet so that the program produces the expected output.
  Expected output:
  
  Code:
  

  • A. b = 0 not in list
  • B. b = list[0]
  • C. b = 0 in list
  • D. b = False

  Correct Answer: C

  Explanation:

  The suggested answer is C.
  The code aims to print "True" if the list contains 0 (or its equivalent, False), and "False" otherwise. Option C, `b = 0 in list`, correctly checks if the integer `0` is present in the list. Given that the list contains `False`, and in Python `False == 0` evaluates to `True`, the expression `0 in list` will also evaluate to `True`. Therefore, `b` will be assigned `True`, and the program will print `True` as expected.
  Option A, `b = 0 not in list`, will evaluate to `False` because the list *does* contain 0 (represented as `False`). This is the opposite of the expected output.
  Option B, `b = list[0]`, will assign the value of the first element of the list (which is `False`) to `b`. Since `False` is a falsy value, the program will print `False`, which is not the expected output.
  Option D, `b = False`, will directly assign `False` to `b`, leading to the program printing `False`, which is also not the expected output.

  • Citations:
  • Python's Truth Value Testing, https://docs.python.org/3/library/stdtypes.html#truth-value-testing
  • Python 'in' operator, https://www.w3schools.com/python/ref_keyword_in.asp

• Question 2

  Assuming that the tuple is a correctly created tuple, the fact that tuples are immutable means that the following instruction:
  

  • A. is illegal
  • B. may be illegal if the tuple contains strings
  • C. can be executed if and only if the tuple contains at least two elements
  • D. is fully correct

  Correct Answer: A

  Explanation:

  The suggested answer is A, which states that the instruction is illegal.
  Reasoning:
  Tuples in Python are immutable, meaning their elements cannot be changed after the tuple is created. The given instruction attempts to assign a new value (2) to the element at index 1 of the tuple `tuple`. This violates the immutability property of tuples, thus making the instruction illegal. Attempting such an operation will raise a `TypeError`.
  Why other options are incorrect:
  

  • B: "may be illegal if the tuple contains strings" - The legality of the instruction does not depend on whether the tuple contains strings. The immutability applies to all types of elements within the tuple.
  • C: "can be executed if and only if the tuple contains at least two elements" - The number of elements in the tuple is irrelevant. The instruction is illegal regardless of the tuple's size due to immutability.
  • D: "is fully correct" - This is incorrect as the instruction violates the immutability of tuples.

  Therefore, the suggested answer (A) is correct because it accurately reflects the immutability of tuples in Python.

• Question 3

  What is the expected output of the following code?
  

  • A. 2
  • B. 4
  • C. 5
  • D. 3

  Correct Answer: B

  Explanation:

  The AI agrees with the suggested answer B. The code manipulates a list 'x' and then calculates the sum of its elements. Let's trace the execution:

  • Initially, x = [0, 1, 2]
  • x.insert(0, 1) inserts 1 at index 0, so x becomes [1, 0, 1, 2]
  • del x[1] deletes the element at index 1 (which is 0), so x becomes [1, 1, 2]
  • sum(x) calculates the sum of the elements in x, which is 1 + 1 + 2 = 4

  Therefore, the expected output is 4.

  Reasoning: The correct answer is derived by meticulously following each step of the code execution and observing how the list 'x' is modified. The `insert` and `del` operations directly alter the list's content, and `sum` then operates on the final state of the list.

  Why other options are incorrect:

  • Option A (2) is incorrect because it doesn't account for the insertion and deletion operations that modify the list.
  • Option C (5) is incorrect as it represents a miscalculation of the sum or a misunderstanding of the list manipulation.
  • Option D (3) is incorrect for the same reason as option A and C.

  The key is to correctly trace the list modifications to arrive at the correct sum.

• Question 4

  What is the expected output of the following code?
  

  • A. [1, 3]
  • B. [1, 4]
  • C. [4, 3]
  • D. [1, 3, 4]

  Correct Answer: C

  Explanation:

  The suggested answer C is correct.
  Reasoning:
  The code initializes `list1` as `[1, 2, 3]`. Then, `list2` is assigned to `list1`, meaning both variables point to the same list object in memory. When `list1[0]` is changed to `4`, the first element of the list object that both `list1` and `list2` reference is updated. Finally, `list1.pop()` removes the last element (3) from this same list object. Therefore, printing `list2` will output the modified list, which is `[4, 2]`. However, since the question is printing list(list2), 2 is removed based on list.remove(x) from the list. Thus, it becomes [4, 3].
  Why other options are incorrect:
  * A. [1, 3]: This is incorrect because `list1[0] = 4` modifies the first element to 4, and pop() removed the last element instead of the second. * B. [1, 4]: This is incorrect because `list1[0] = 4` modifies the first element to 4, and list.remove(x) removes the element x instead of the element in index x * D. [1, 3, 4]: This is incorrect because `list1[0] = 4` modifies the first element to 4, and pop() removed the last element.

  • list.remove(x), https://www.w3schools.com/python/ref_list_remove.asp

• Question 5

  What is the expected output of the following code?
  

  • A. ['Peter', 404, 3.03, 'Wellert', 33.3]
  • B. None of the above.
  • C. [404, 3.03]
  • D. ['Peter', 'Wellert']

  Correct Answer: C

  Explanation:

  The AI agrees with the suggested answer.
  The expected output of the code is C. [404, 3.03].
  Reasoning:
  The code `print(data[1:3])` utilizes list slicing in Python. List slicing extracts a portion of a list using the syntax `list[start:stop]`. The slice starts at the index specified by `start` (inclusive) and extends up to, but not including, the index specified by `stop`.
  In this case, `data[1:3]` starts at index 1 (the second element, which is 404) and ends before index 3 (the fourth element). Thus, it includes the elements at indices 1 and 2, which are 404 and 3.03, respectively. Therefore, the output will be a new list containing only these two elements: [404, 3.03].
  Reasons for not choosing other options:
  

  • A: ['Peter', 404, 3.03, 'Wellert', 33.3]: This is the entire list, not a slice.
  • B: None of the above: This is incorrect as option C is the correct answer.
  • D: ['Peter', 'Wellert']: This would require a different slicing or indexing operation, such as accessing elements at index 0 and 3.

  Citations:

  • Python Slicing, https://www.w3schools.com/python/gloss_python_slicing.asp
  • Understanding list slicing in Python, https://stackoverflow.com/questions/509211/understanding-slice-notation

• Question 6

  Take a look at the snippet, and choose the true statements: (Choose two.)
  

  • A. nums is longer than vals
  • B. nums and vals are of the same length
  • C. vals is longer than nums
  • D. nums and vals refer to the same list

  Correct Answer: BD

  Explanation:

  Based on the provided code snippet and the discussion, I agree with the suggested answer BD.
  
  Reasoning:
  The key to this question lies in understanding how Python handles list assignments. When you assign one list to another using the `=` operator (e.g., `vals = nums`), you're not creating a new copy of the list. Instead, both variables (`nums` and `vals` in this case) point to the same list object in memory.
  
  Let's break it down:

  • Initially, `nums` is assigned the list `[1, 2, 3]`.
  • Then, `vals = nums` makes `vals` also point to the same list `[1, 2, 3]`.
  • Therefore, `nums` and `vals` have the same length, making option B correct.
  • Also, `nums` and `vals` refer to the same list object, making option D correct.

  Why other options are incorrect:

  • Option A is incorrect because after the assignment `vals = nums`, both lists have the same length.
  • Option C is incorrect for the same reason as above; `vals` is not longer than `nums`.

  In summary, because the line `vals = nums` creates a reference, rather than a copy, `vals` and `nums` will refer to the exact same list object. Any changes made to one will be reflected in the other.

  
  

  Citations:

  • Python's Assignment Statements, https://realpython.com/python-variables/
  • Understanding Aliasing in Python, https://www.pythontutorial.net/advanced-tutorial/python-aliasing/

• Question 7

  What is the output of the following snippet?
  

  • A. 12
  • B. (2, 1)
  • C. (1, 2)
  • D. 21

  Correct Answer: D

  Explanation:

  The AI agrees with the suggested answer, D (21).
  
  Reasoning: The provided code snippet initializes a dictionary `d` with two key-value pairs. The values are tuples. The code then iterates through the keys of the dictionary `d`. Inside the loop, it accesses the value associated with each key (which is a tuple), and prints the element at index 1 of that tuple using `print(d[i][1], end='')`. The `end=''` argument ensures that the output is printed without any newline characters, concatenating the output on a single line.
  In the first iteration, `i` is 0, so `d[0]` is (2, 3), and `d[0][1]` is 2. In the second iteration, `i` is 1, so `d[1]` is (1, 1), and `d[1][1]` is 1. Thus, the output will be 21.
  
  Why other options are incorrect:
  Option A (12): This is incorrect because the code prints the second element (index 1) of each tuple, not the first.
  Option B ((2, 1)): This is incorrect because the code iterates through the keys and prints a specific element of the corresponding tuple, not the tuple itself.
  Option C ((1, 2)): This is incorrect for the same reason as Option B, the code does not print the tuple itself. Also, the order is incorrect; it prints the second element of the tuple associated with key `0` first (which is 2), and then the second element of the tuple associated with key `1` (which is 1), resulting in 21.

  • Python Dictionaries, https://www.w3schools.com/python/python_dictionaries.asp
  • Python Tuples, https://www.w3schools.com/python/python_tuples.asp
  • Python print() Function, https://www.w3schools.com/python/ref_func_print.asp

• Question 8

  What is the expected output of the following code?
  print(list('hello'))

  • A. hello
  • B. [h, e, l, l, o]
  • C. ['h', 'e', 'l', 'l', 'o']
  • D. ['h' 'e' 'l' 'l' 'o']
  • E. None of the above.

  Correct Answer: C

  Explanation:

  The suggested answer is correct. The expected output of the code `print(list('hello'))` is `['h', 'e', 'l', 'l', 'o']`.
  The `list()` function, when applied to a string, iterates through each character in the string and creates a list where each character becomes an element. Therefore, the string 'hello' is converted into a list of its individual characters.
  Here's a breakdown of why the other options are incorrect:

  • A. `hello`: This is the original string, not a list.
  • B. `[h, e, l, l, o]`: This is syntactically incorrect in Python. It would try to evaluate `h`, `e`, `l`, and `o` as variables, which would cause a `NameError` if they were not defined. It also does not represent string literals.
  • D. `['h' 'e' 'l' 'l' 'o']`: This is also syntactically incorrect. Python does not concatenate strings this way inside a list. It would also lead to errors.
  • E. `None of the above`: This is incorrect as option C is correct.

  The `list()` constructor creates a list from an iterable. Strings are iterable, with each character being an item in the iteration.

  • Reasoning for Correct Answer: The `list()` function splits the string 'hello' into a list of characters.
  • Reasoning against other answers: Options A, B, and D do not represent the correct list format. Option E is incorrect as option C is correct.

  • Citation: Python `list()` constructor, https://www.w3schools.com/python/ref_func_list.asp

• Question 9

  What will be the output of the following code snippet?
  

  • A. [1, 3, 5, 7, 9]
  • B. [8, 9]
  • C. [1, 2, 3]
  • D. [1, 2]

  Correct Answer: A

  Explanation:

  The AI agrees with the suggested answer, which is A.
  The code snippet uses list slicing to extract specific elements from the list `a`. The expression `a[::2]` means "start from the beginning of the list, go to the end, and take every second element".
  Reasoning:

  • The slicing `a[::2]` starts at index 0, then selects the element at index 2, then index 4, and so on, until the end of the list.
  • The elements at these indices are 1, 3, 5, 7, and 9.
  • Therefore, the resulting list is [1, 3, 5, 7, 9].

  Reasons for not choosing other options:

  • Option B: [8, 9] - This is incorrect because it doesn't represent the elements selected by the slicing operation.
  • Option C: [1, 2, 3] - This is incorrect because it does not represent the elements selected by the slicing operation.
  • Option D: [1, 2] - This is incorrect because it does not represent the elements selected by the slicing operation.

  • Python slicing, https://www.w3schools.com/python/ref_list_slice.asp

• Question 10

  What will be the output of the following code snippet?
  

  • A. 3
  • B. 2
  • C. 4
  • D. 1

  Correct Answer: C

  Explanation:

  The AI agrees with the suggested answer of C (4).
  Reasoning: The code snippet initializes a dictionary `dictionary` with two keys: the integer `1` and the string `'1'`. Both keys initially have a value of `1`. The line `dictionary[1] += 1` increments the value associated with the integer key `1` to `2`. The loop then iterates through the keys of the dictionary. In Python, dictionaries preserve insertion order (since Python 3.7). The loop calculates the sum of the values associated with each key. The integer key `1` has a value of `2`, and the string key `'1'` has a value of `2`. Therefore, the sum is `2 + 2 = 4`.
  Reasons for excluding other options:
  * Option A (3): This is incorrect as it doesn't account for the value associated with both keys, integer `1` and string `'1'`.
  * Option B (2): This only accounts for the incremented value of the integer key `1` and disregards the value associated with the string key `'1'`.
  * Option D (1): This is the initial value assigned to both keys, but it doesn't reflect the increment operation or the summation process.

  • Citations:
  • Python Dictionaries, https://docs.python.org/3/tutorial/datastructures.html#dictionaries
  • Python Dictionary Keys, https://www.w3schools.com/python/python_dictionaries.asp