WGU Updated Foundations-of-Computer-Science Exam Questions and Answers by erick

An ndarray is NumPy’s fundamental data structure: ann-dimensional arraydesigned for efficient numerical computation. The term stands for “N-dimensional array,” and it is implemented as numpy.ndarray. Unlike Python’s built-in list, an ndarray stores elements in a compact, homogeneous format defined by its dtype (such as integers or floating-point numbers). This uniform representation enables fast, vectorized operations and efficient use of memory, which is why ndarray is central in scientific computing and data analysis.

An ndarray supports multiple dimensions: a 1D array behaves like a vector, a 2D array like a matrix (rows and columns), and higher-dimensional arrays represent tensors. Textbooks emphasize that ndarray operations are typically element-wise by default (for example, a + b adds corresponding elements), and that slicing and broadcasting allow powerful computations without explicit loops. This approach is both expressive and efficient because the heavy lifting happens in optimized low-level code.

Option A is incorrect because ndarray is not built into core Python; it comes from NumPy. Option B describes a tree, which is a different data structure entirely. Option D is incorrect because sockets and XML-related functionality belong to other parts of Python’s standard library, not to NumPy or ndarray.

In short, an ndarray is the primary array object of NumPy, providing high-performance multi-dimensional numerical storage and computation.

Python usesdynamic typing, a core concept emphasized in programming language textbooks. In dynamically typed languages, a variable name does not permanently “own” a type. Instead, theobjectcreated by an expression has a type, and the variable becomes a reference to that object. Therefore, the type associated with a variable at any moment is determined by the value assigned to it. For example, after x = 7, x refers to an integer object. After x = "seven", the same name now refers to a string object. The type changes because the binding changes, not because the variable’s type declaration was edited.

Option A describesstatic typingsystems (common in languages like Java, C, or C++), where programmers declare types and compilers enforce them. Python does not require such declarations for ordinary variables. Option B is incorrect because type assignment is deterministic, not random. Option C is incorrect because Python does not default variables to strings; it assigns whatever type results from the right-hand-side expression.

This model is closely tied to Python’s runtime behavior: type checks occur during execution, and functions can accept values of different types as long as the operations used are valid (often discussed as “duck typing”). This flexibility supports rapid development, but also motivates careful testing and, in larger systems, optional type hints for documentation and tool support.

Binary search is designed for searching in asorted (ordered) sequence. Its efficiency comes from repeatedly comparing the target to the middle element and discarding half of the remaining search space. This halving logic only works when the data is ordered, because the algorithm relies on the guarantee that all elements on one side of the midpoint are smaller (or larger) than the midpoint. In textbooks, this requirement is stated explicitly: binary search assumes the collection is sorted according to the same ordering used for comparisons.

An “ordered list” is therefore the correct focus among the options. Binary search can be implemented on arrays or other random-access structures where you can quickly access the middle element by index. While you can conceptually perform binary search on a linked list, it becomes inefficient because finding the middle requires linear traversal, losing the O(log n) advantage. Stacks and queues are not appropriate because they restrict access to ends only (LIFO for stacks, FIFO for queues), preventing direct access to the midpoint and making the binary search strategy infeasible.

Thus, the central requirement for binary search is a sorted/ordered sequence, typically supporting efficient indexing, which is why the correct choice is an ordered list.

Selection sort works by maintaining a boundary between a sorted prefix and an unsorted suffix. On each pass, the algorithm finds the smallest value in the unsorted portion and places it into the first position of that unsorted portion (which is also the next position in the sorted prefix). This is usually done by swapping the element at the minimum’s index with the element at the boundary index (the “first unsorted element”). That description matches option D.

If the first element of the unsorted portion is already the smallest, then the minimum’s index equals the boundary index. In textbook implementations, the algorithm may still execute a swap operation, but it becomes a swap of an element with itself (a no-op), leaving the array unchanged. Many implementations include a small optimization: perform the swap only if the minimum index differs from the boundary index. Either way, conceptually the “action taken” by selection sort is still “swap the selected minimum into the first unsorted position,” which is exactly what option D states.

Options A and B are unrelated to sorting; selection sort never increases or duplicates values. Option C is incorrect because selection sort swaps the minimum with thefirstunsorted element, not the last. After the swap (or no-op), the sorted region grows by one element, and the algorithm repeats from the next boundary position.

This logic is fundamental for understanding how selection sort ensures correctness: after pass i, the smallest i+1 elements are fixed in their final positions.