AP Computer Science Principles - Practice Exam (70 MCQ)

AP Computer Science Principles Practice Exam

70 Multiple Choice Questions - Enhanced Difficulty

Includes Multi-Select, Reading Passage, and Error Analysis Questions

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About This Practice Exam

70 AP-style questions matching official exam format
57 single-select + 8 multi-select + 5 passage-based questions
Includes challenging formats: error-finding, I/II/III analysis, NOT/EXCEPT
Auto-grading with detailed explanations and AP score estimate (1-5)

Instructions: For multi-select questions (marked with red badge), select ALL correct answers. Read questions carefully - watch for NOT, EXCEPT, and LEAST.

Question 1

The following procedure is intended to return the sum of all even numbers in a list, but it contains an error.

PROCEDURE sumEvens(numList) { total ← 0 FOR EACH num IN numList { IF (num MOD 2 = 1) { total ← total + num } } RETURN (total) }

Which change will make the procedure work as intended?

A. Change total ← 0 to total ← 1 B. Change num MOD 2 = 1 to num MOD 2 = 0 C. Change total ← total + num to total ← total + 2 D. Change RETURN (total) to RETURN (total * 2)

Question 2

Consider the following statements about Internet protocols:

TCP includes mechanisms for error checking and retransmission of lost packets.
IP is responsible for addressing and routing packets between devices.
HTTP encrypts all data transmitted between a web browser and server.

Which of the statements above are TRUE?

A. I only B. III only C. I and II only D. I, II, and III

Question 3

All of the following are examples of lossy compression EXCEPT:

A. Converting a WAV audio file to MP3 format B. Saving a BMP image as a JPEG file C. Compressing a folder of text files into a ZIP archive D. Streaming video at 480p instead of 4K resolution

Question 4

Consider the following code segment:

list ← [3, 1, 4, 1, 5, 9] result ← 0 i ← 1 REPEAT UNTIL (i > LENGTH(list)) { IF (list[i] > list[i + 1]) { result ← result + 1 } i ← i + 2 } DISPLAY(result)

What is displayed when this code runs? (Assume 1-based indexing)

A. 1 B. 2 C. 3 D. 4

Question 5

A researcher collects data on student study habits and test scores. Which question can NOT be answered using only this data?

A. Is there a correlation between hours studied and test scores? B. What percentage of students studied more than 10 hours? C. Does studying cause higher test scores? D. What was the average test score for students who studied 5-10 hours?

Question 6

A student wrote the following procedure to count how many times a target value appears in a list. The procedure does NOT work correctly.

PROCEDURE countOccurrences(myList, target) { count ← 0 index ← 1 REPEAT UNTIL (index > LENGTH(myList)) { IF (myList[index] = target) { count ← count + 1 RETURN (count) } index ← index + 1 } RETURN (count) }

For the call countOccurrences([2, 5, 2, 8, 2], 2), the procedure returns 1 instead of the correct answer 3. Which change fixes the error?

A. Change count ← 0 to count ← 1 B. Change index ← 1 to index ← 0 C. Remove the line RETURN (count) from inside the IF block D. Change count ← count + 1 to count ← index

Question 7

In public-key cryptography, Alice wants to send a confidential message to Bob. Which keys should be used?

A. Alice encrypts with her public key; Bob decrypts with his private key B. Alice encrypts with Bob's public key; Bob decrypts with his private key C. Alice encrypts with her private key; Bob decrypts with Alice's public key D. Alice encrypts with Bob's private key; Bob decrypts with his public key

Question 8

A game uses a unique identifier for each player. The developers expect a maximum of 100,000 players. What is the minimum number of bits needed to represent all possible player IDs?

A. 16 bits B. 17 bits C. 18 bits D. 20 bits

Question 9

Consider the following statements about procedural abstraction:

It allows programmers to use a procedure without knowing the details of its implementation.
It always improves the runtime efficiency of a program.
It helps manage complexity in large programs by breaking them into smaller, reusable parts.

Which of the statements above are TRUE?

A. I only B. II only C. I and III only D. I, II, and III

Question 10

Algorithm A takes 1 second to process a list of 1,000 items. Algorithm B takes 2 seconds for the same list. When processing 2,000 items, Algorithm A takes 4 seconds while Algorithm B takes 4 seconds. Which statement is MOST likely true?

A. Algorithm A is always faster than Algorithm B B. Algorithm A has quadratic time complexity; Algorithm B has linear time complexity C. Algorithm B will become faster than Algorithm A for larger inputs D. Both algorithms have the same time complexity

Question 11

Consider the Boolean expression: NOT (x AND y) OR z

If x = true, y = false, and z = false, what is the value of this expression?

A. true B. false C. Cannot be determined without additional information D. The expression is invalid

Question 12

What value is displayed when the following code executes?

total ← 0 FOR i ← 1 TO 3 { FOR j ← 1 TO i { total ← total + 1 } } DISPLAY(total)

A. 3 B. 6 C. 9 D. 12

Question 13

Which of the following would LEAST likely help reduce the digital divide?

A. Providing subsidized Internet access to low-income households B. Creating public computer labs in community centers C. Developing faster 5G networks in urban business districts D. Offering digital literacy training programs for seniors

Question 14

A city uses a simulation to model traffic patterns and test the impact of adding a new highway exit. Which statement about this simulation is FALSE?

A. The simulation can be run multiple times with different parameters B. The simulation results depend on the assumptions built into the model C. The simulation will produce exactly the same traffic patterns as real life D. The simulation is less expensive than building the actual highway exit to test

Question 15

Which of the following problems is undecidable?

A. Determining whether a given number is prime B. Determining whether two programs will always produce the same output for all inputs C. Finding the shortest path between two nodes in a graph D. Sorting a list of numbers in ascending order

Question 16

What is the value of result after the following code executes?

word ← "COMPUTER" result ← "" FOR i ← 1 TO LENGTH(word) { IF (i MOD 2 = 1) { result ← result + word[i] } } DISPLAY(result)

A. "CMUE" B. "OPTR" C. "COMPUTER" D. "CMTR"

Question 17

A digital photograph contains both the image data and metadata. Which of the following is typically stored as metadata rather than image data?

A. The RGB color values of each pixel B. The GPS coordinates where the photo was taken C. The brightness level of the center pixel D. The compressed binary representation of the image

Question 18

A sequential program takes 100 seconds to complete. When parallelized across 4 processors, it takes 40 seconds. Which statement BEST explains this result?

A. The program achieved perfect speedup with 4 processors B. Some portions of the program could not be parallelized C. The parallel version introduced bugs that slowed execution D. Four processors are not enough to parallelize the program

Question 19

A robot is in a 5x5 grid, starting at position (1, 1) facing right. The following commands are available: MOVE_FORWARD(), ROTATE_LEFT(), ROTATE_RIGHT(). What is the robot's position after executing this code?

REPEAT 2 TIMES { MOVE_FORWARD() MOVE_FORWARD() ROTATE_LEFT() }

A. (3, 3) facing left B. (3, 3) facing up C. (5, 3) facing up D. (3, 5) facing left

Question 20

A company uses crowdsourcing to have thousands of users classify images as "cat" or "not cat." Which is a potential limitation of this approach?

A. It is more expensive than hiring a single expert B. Individual contributors may make errors or submit low-quality responses C. The task cannot be divided among multiple people D. Crowdsourcing requires all participants to be in the same location

Question 21

Binary search can be used to efficiently find a value in a list. Which condition must be true for binary search to work correctly?

A. The list must contain no duplicate values B. The list must be sorted C. The list must have an odd number of elements D. The list must contain only positive integers

Question 22

Consider the following procedure:

PROCEDURE mystery(a, b) { IF (a < b) { RETURN (mystery(a + 1, b)) } ELSE { RETURN (a) } }

What does mystery(3, 7) return?

A. 3 B. 7 C. 10 D. The procedure never terminates

Question 23

An employee receives a phone call from someone claiming to be from IT support, asking for their password to "fix an urgent system issue." This is an example of:

A. A brute-force attack B. A DDoS attack C. A social engineering attack D. A man-in-the-middle attack

Question 24

Consider the following code segment:

list ← [10, 20, 30, 40] REMOVE(list, 2) INSERT(list, 2, 25) APPEND(list, 50) DISPLAY(list)

What is displayed? (Assume 1-based indexing where REMOVE removes the element at that index)

A. [10, 25, 30, 40, 50] B. [10, 20, 25, 30, 40, 50] C. [10, 25, 40, 50] D. [25, 10, 30, 40, 50]

Question 25

Which Boolean expression is logically equivalent to NOT (A OR (B AND C))?

A. (NOT A) AND (NOT B OR NOT C) B. (NOT A) OR (NOT B AND NOT C) C. (NOT A) AND (NOT B) AND (NOT C) D. (NOT A) OR (NOT B) OR (NOT C)

Question 26

A programmer is testing a procedure and finds that it produces incorrect output for certain inputs but works correctly for others. Which debugging strategy would be MOST effective?

A. Rewriting the entire procedure from scratch B. Adding print statements to display intermediate values during execution C. Only testing inputs that are known to produce correct output D. Removing all comments from the code

Question 27

Consider the following statements about bias in computing systems:

Bias can be introduced when training data does not represent all groups equally.
Algorithms are objective and cannot reflect human biases.
Facial recognition systems have shown different accuracy rates across demographic groups.

Which of the statements above are TRUE?

A. I only B. II only C. I and III only D. I, II, and III

Question 28

What is displayed when this code executes?

nums ← [2, 4, 6, 8, 10] result ← 1 FOR EACH n IN nums { IF (n < 7) { result ← result * n } } DISPLAY(result)

A. 12 B. 48 C. 240 D. 3840

Question 29

When a user types "www.example.com" into a web browser, which protocol is used to translate this domain name into an IP address?

A. HTTP B. DNS C. TCP D. SSL

Question 30

A team of four programmers is collaborating on a software project. They use a version control system (like Git) to manage their code. Which benefit does this provide?

A. It automatically fixes all bugs in the code B. It allows team members to work on different parts simultaneously and merge changes C. It prevents anyone from modifying the code without consensus D. It eliminates the need for testing

Question 31

A procedure is designed to find the second largest value in a list. Which test case would NOT be useful for testing edge cases?

A. A list with exactly two elements B. A list where all elements are the same C. A list of 100 unique positive integers D. A list with only one element

Question 32

What is the output of the following code?

x ← 5 y ← 3 temp ← x x ← y y ← temp DISPLAY(x) DISPLAY(y)

A. 5, 3 B. 3, 5 C. 5, 5 D. 3, 3

Question 33

All of the following are true about heuristic algorithms EXCEPT:

A. They provide approximate solutions rather than guaranteed optimal solutions B. They are useful when exact solutions would take too long to compute C. They always produce the same result for a given input D. They are used in complex optimization problems like the traveling salesman problem

Question 34

An 8-bit binary number can represent unsigned integers in what range?

A. 0 to 127 B. 0 to 255 C. 1 to 256 D. -128 to 127

Question 35

Which statement about HTTPS is TRUE?

A. HTTPS prevents websites from tracking user activity B. HTTPS encrypts data transmitted between browser and server C. HTTPS makes web pages load faster than HTTP D. HTTPS is only used for banking websites

Question 36

A procedure takes a list of numbers and returns a new list containing only the numbers that appear more than once. What type of operation does this primarily involve?

A. Sorting B. Filtering C. Aggregating D. Encrypting

Question 37

A programmer writes a library of math functions to use in multiple projects. This is an example of:

A. Code obfuscation B. Code reuse through modularity C. Code compilation D. Code encryption

Question 38

What is the decimal equivalent of the binary number 11010110?

A. 182 B. 214 C. 208 D. 246

Question 39

The following code is intended to count how many numbers in a list are between 10 and 20 (inclusive). What is wrong?

PROCEDURE countInRange(myList) { count ← 0 FOR EACH num IN myList { IF (num > 10 AND num < 20) { count ← count + 1 } } RETURN(count) }

A. The loop should use indices instead of FOR EACH B. The condition excludes 10 and 20 but should include them C. The count variable should start at 1 D. AND should be replaced with OR

Question 40

A website implements rate limiting to prevent brute-force attacks. What does this mean?

A. Users must complete a CAPTCHA before logging in B. Failed login attempts are tracked and access is temporarily blocked after too many failures C. Passwords must contain special characters D. Two-factor authentication is required

Question 41

Which factor is LEAST likely to contribute to computing bias?

A. Training data that underrepresents certain populations B. Developers making assumptions based on their own experiences C. Using a faster computer to run the algorithm D. Historical data that reflects past discriminatory practices

Question 42

What is displayed?

a ← 10 b ← 3 c ← a MOD b d ← a / b DISPLAY(c + d)

A. 4 B. 4.33 C. 5 D. Approximately 4.33

Question 43

A network has multiple paths between any two computers. This design principle is called:

A. Encryption B. Redundancy C. Compression D. Authentication

Question 44

Which of the following BEST describes an API?

A. A set of protocols that encrypt all web traffic B. A specification that allows different software systems to communicate C. A device that routes packets between networks D. A programming language used for web development

Question 45

What is displayed after this code runs?

list ← ["a", "b", "c", "d"] i ← LENGTH(list) result ← "" REPEAT UNTIL (i < 1) { result ← result + list[i] i ← i - 1 } DISPLAY(result)

A. "abcd" B. "dcba" C. "dcb" D. ""

Question 46

Open-source software licensing typically allows users to:

A. View, modify, and distribute the source code B. Use the software only for non-commercial purposes C. Claim the software as their own original work D. Sell the software without attribution

Question 47

A streaming service uses machine learning to recommend shows. This system learns from:

A. Explicit programming rules written by developers B. Patterns in user viewing history and preferences C. Random selection algorithms D. Direct user feedback surveys only

Question 48

What type of error does the following code contain?

PROCEDURE average(numList) { sum ← 0 FOR EACH num IN numList { sum ← sum + num } RETURN (sum / LENGTH(numList)) }

A. Syntax error - incorrect loop structure B. Runtime error - division by zero if list is empty C. Logic error - sum should start at 1 D. The code has no errors

Question 49

Which of the following is the BEST example of using abstraction in program design?

A. Writing detailed comments for every line of code B. Creating a procedure called "sortList" that hides the sorting algorithm details C. Copying and pasting code instead of using procedures D. Using meaningful variable names

Question 50

Internet packets traveling from New York to Los Angeles may take different routes. Which statement explains why?

A. Routers dynamically select paths based on current network conditions B. Each packet is assigned a random route by the sender C. The Internet only has one path between any two locations D. Users manually choose the route for each packet

Question 51

What is displayed?

x ← 64 count ← 0 REPEAT UNTIL (x ≤ 1) { x ← x / 2 count ← count + 1 } DISPLAY(count)

A. 5 B. 6 C. 7 D. 32

Question 52

A company's privacy policy states they collect user data for "improving services." This data could potentially be used for all of the following EXCEPT:

A. Training machine learning algorithms B. Selling aggregated data to advertisers C. Guaranteeing the user's data will never be accessed by hackers D. Analyzing usage patterns to improve user experience

Question 53

A procedure uses random values to simulate rolling two dice and returns their sum. Running the procedure twice:

A. Will always return the same result B. May return different results C. Will always return 7 D. Cannot be predicted without knowing the random seed

Question 54

Overflow errors occur when:

A. A program runs out of memory B. A calculation produces a result too large to be stored in the available bits C. A variable is assigned a string instead of a number D. An array index is out of bounds

Question 55

A programmer wants to document their code so others can understand it. Which is MOST important to include?

A. The date and time each line was written B. The purpose of each procedure and what parameters it expects C. A comment for every single line of code D. The programmer's personal opinions about the code

Question 56

Which correctly represents the iterative development process?

A. Design, Code, Test, Deploy, Never modify B. Plan, Develop, Test, Refine, Repeat C. Write all code first, then test everything at the end D. Test, Code, Design, Deploy

Question 57

Two computers on different continents communicate via the Internet. Which is TRUE about this communication?

A. Data travels through a single dedicated cable between them B. Data is broken into packets that may travel different routes C. Both computers must use the same operating system D. Direct communication is impossible without a VPN

Multi-Select Questions (58-65): Select ALL correct answers

Question 58 Select TWO answers

Which TWO of the following are potential benefits of using cloud computing?

A. Data is always 100% secure from breaches B. Users can access files and applications from any Internet-connected device C. Computing resources can be scaled up or down based on demand D. No Internet connection is ever required

Question 59 Select TWO answers

Which TWO of the following are characteristics of lossless data compression?

A. The original file can be perfectly reconstructed from the compressed file B. It typically achieves higher compression ratios than lossy compression C. It is commonly used for text files and program code D. Some data is permanently discarded to reduce file size

Question 60 Select TWO answers

Which TWO of the following help protect against phishing attacks?

A. Verifying the sender's email address and checking for suspicious links before clicking B. Using the same password for all accounts C. Enabling two-factor authentication on accounts D. Disabling all firewall protections

Question 61 Select TWO answers

Which TWO of the following are true about algorithms?

A. An algorithm must be written in a specific programming language B. An algorithm is a step-by-step process for solving a problem C. Different algorithms can solve the same problem with different efficiencies D. All algorithms run in constant time

Question 62 Select TWO answers

Which TWO are potential negative impacts of computing innovations?

A. Increased efficiency in many industries B. Job displacement due to automation C. Erosion of privacy through data collection D. Faster communication across the globe

Question 63 Select TWO answers

Which TWO are benefits of procedural abstraction?

A. Procedures can be reused in multiple parts of a program B. Programs run faster when using procedures C. Complex programs become easier to read and maintain D. Procedures eliminate all bugs from programs

Question 64 Select TWO answers

A researcher analyzes a dataset of hospital patient records. Which TWO questions can likely be answered from this data?

A. What is the average length of stay for patients with a specific diagnosis? B. Whether patients were satisfied with their care C. Which medications were prescribed most frequently D. What patients thought about the hospital food

Question 65 Select TWO answers

Which TWO practices help ensure fault tolerance in a system?

A. Having multiple servers that can take over if one fails B. Using a single central server for all operations C. Regularly backing up data to multiple locations D. Removing all redundant components to simplify the system

Reading Passage Questions (66-70)

Computing Innovation: Autonomous Delivery Robots

Several companies have deployed autonomous delivery robots in urban areas. These robots use a combination of GPS, cameras, and machine learning algorithms to navigate sidewalks and deliver packages to customers.

The robots collect extensive data during operation, including video of their surroundings, GPS coordinates, delivery times, and information about obstacles encountered. This data is transmitted to company servers and used to improve the robots' navigation algorithms.

Early deployments have shown both benefits and challenges. Delivery robots can reduce traffic congestion by replacing some delivery truck trips, and they can make deliveries at times when human drivers are unavailable. However, they have been criticized for blocking sidewalks, creating accessibility issues for wheelchair users, and raising privacy concerns about constant video recording in public spaces.

The robots operate on battery power and return to charging stations between deliveries. Their range is limited to a few miles, making them most effective for short-distance deliveries in dense urban areas.

Question 66

Based on the passage, which data collected by the robots is used to improve their performance?

A. Customer satisfaction surveys B. Video, GPS, and obstacle information used to train navigation algorithms C. Financial data about delivery costs D. Personal information about package recipients

Question 67

According to the passage, which is a potential harmful effect of the delivery robots?

A. They increase traffic congestion B. They may create accessibility barriers for people with disabilities C. They require human drivers to operate D. They can only operate during business hours

Question 68

The passage mentions that robots collect video of their surroundings. This raises concerns most closely related to which computing concept?

A. Lossy compression B. Privacy and data collection C. Parallel computing D. Binary representation

Question 69

The robots use "machine learning algorithms to navigate." Based on your knowledge of machine learning, this means the robots:

A. Follow a fixed set of rules programmed by developers B. Improve their navigation by learning from patterns in collected data C. Are controlled remotely by human operators D. Can only navigate on pre-mapped routes

Question 70

Based on the passage, which would be the MOST appropriate use case for these delivery robots?

A. Delivering packages across the country B. Making short-distance deliveries in a downtown area C. Delivering to rural homes 20 miles from the warehouse D. Transporting heavy industrial equipment

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AP Computer Science Principles - Practice Exam (70 MCQ)

AP Computer Science Principles Practice Exam

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Computing Innovation: Autonomous Delivery Robots

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