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AP Computer Science Principles Hard practice

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Hard practice

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Question 1

Which of the following is an example of data abstraction?

A.Storing a student's grade as the number 92 rather than tracking every individual assignment score that contributed to it.B.Compressing an image file so it takes up less disk space.C.Converting a decimal number to binary so a computer can store it.D.Encrypting a file so unauthorized users cannot read it.

Question 2

A recursive procedure power(base, exp) computes base raised to the power exp using the rule: power(base, exp) = base * power(base, exp - 1), with the base case power(base, 0) = 1.

How many total calls to power (including the initial call) are made when computing power(3, 4)?

A.3B.4C.5D.12

Question 3

A digital audio file encodes sound by sampling the audio signal at regular intervals (e.g., 44,100 times per second) and storing each sample as a binary number. Which of the following changes would INCREASE the accuracy of the digital audio representation?

A.Reducing the sampling rate from 44,100 Hz to 22,050 Hz.B.Using fewer bits per sample (e.g., from 16 bits to 8 bits).C.Increasing the sampling rate (e.g., from 44,100 Hz to 96,000 Hz) and using more bits per sample.D.Applying lossy compression to the sampled audio data.

Question 4

A researcher studying online misinformation downloads 10 million public tweets using Twitter's API and analyzes which types of false claims spread fastest. The tweets are publicly posted but the users did not know their data would be used for research.

Which of the following BEST represents the ethical tension in this scenario?

A.There is no ethical tension — public data can always be used for any purpose without ethical concerns.B.The ethical tension is between the public benefit of misinformation research and the users' reasonable expectation that their posts, while public, would not be systematically collected and analyzed without consent.C.The only ethical issue is that the researcher is using too much storage space by downloading 10 million tweets.D.The ethical tension is entirely resolved by Twitter's terms of service, which permit API access to public tweets.

Question 5

Which of the following problems has a REASONABLE (polynomial-time) algorithm, and which is considered to have only UNREASONABLE (exponential-time) algorithms for large inputs?

Problem I: Sorting a list of n numbers
Problem II: Checking all possible subsets of n items to find a subset that sums to a target value (brute-force subset sum)

A.Both problems have reasonable (polynomial-time) algorithms.B.Problem I has a reasonable algorithm (e.g., merge sort runs in O(n log n)); Problem II (brute-force) has an unreasonable exponential-time algorithm.C.Both problems have only unreasonable (exponential-time) algorithms.D.Problem I is unreasonable because you must compare every pair of elements; Problem II is reasonable because you stop as soon as you find a valid subset.

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Question 6

A program runs four tasks. Tasks A and B can run in parallel (no dependencies between them). Task C depends on the output of Task A. Task D depends on the outputs of both B and C.

Task A: 3 seconds
Task B: 5 seconds
Task C: 2 seconds (starts after A)
Task D: 1 second (starts after B and C both finish)

Assuming unlimited parallel processors, what is the minimum time to complete all four tasks?

A.6 secondsB.8 secondsC.11 secondsD.5 seconds

Question 7

A company's website is attacked by a botnet — thousands of compromised computers simultaneously send requests to the website, overwhelming its server and making it unavailable to legitimate users.

This attack is called a:

A.SQL injection attackB.Distributed Denial-of-Service (DDoS) attackC.Man-in-the-middle attackD.Phishing attack

Question 8

A health app automatically logs a user's GPS location every 5 minutes throughout the day. Over a year, this produces a detailed record of everywhere the user went.

Which of the following BEST describes a privacy concern raised by this data collection practice?

A.The GPS data uses too many bits per coordinate, wasting storage space.B.Aggregating location data over time creates a detailed behavioral profile that can reveal sensitive information (home/work address, medical visits, religious attendance) even if each data point seems harmless.C.GPS coordinates are stored as floating-point numbers, which introduces rounding errors that distort the user's location.D.The app should use lossless compression on the location data to prevent privacy breaches.

Question 9

A student is developing an app to help users log daily exercise. During testing, a user reports: "When I enter 0 minutes of exercise, the app crashes." The student had not considered zero as a valid input.

This situation illustrates which challenge in program development?

A.Compilation errors — the code cannot be translated to machine instructions.B.Undecidable problems — it is theoretically impossible to determine whether any input will cause a crash.C.Incomplete specification — the original program design did not account for all valid inputs, leading to unexpected behavior.D.Hardware failure — the device cannot process a zero value correctly.

Question 10

Two students are collaborating on a program. Student A writes the data-storage module and Student B writes the display module. They agree that the display module will call getData() to retrieve values, regardless of how Student A internally stores the data.

This agreement BEST demonstrates which concept?

A.Iteration — repeatedly refining the interface until both students agree.B.Abstraction via a defined interface — the display module interacts with stored data through getData() without needing to know the internal implementation.C.Debugging — finding and fixing errors in the communication between modules.D.Sequential development — Student A must finish completely before Student B can begin.

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Question 11

A delivery company needs to find a route that visits 30 cities and returns home with the lowest total distance. An exact algorithm guaranteed to find the optimal route would take an impractically long time. Which approach is MOST appropriate?

A.Use a heuristic (e.g., "always travel to the nearest unvisited city next") that finds a good — but not necessarily optimal — route quickly.B.Always use the exact algorithm because correctness matters more than speed.C.Skip the routing problem and have drivers pick routes manually.D.Use a random ordering of cities each time.

Question 12

Which of the following BEST describes the difference between a problem that has a reasonable algorithm and one that requires an unreasonable algorithm in the CSP framework?

A.Reasonable algorithms always terminate; unreasonable algorithms may run forever.B.Reasonable algorithms run in time that grows polynomially with input size; unreasonable algorithms grow exponentially (or faster), so they become impractical even on modest inputs.C.Reasonable algorithms use less memory; unreasonable algorithms always run out of memory.D.Reasonable algorithms are guaranteed to find an optimal answer; unreasonable ones only approximate.

Question 13

A wireless network uses radio waves to transmit data from a laptop to a router. The router connects to the Internet via a fiber optic cable. At each step in this transmission, what is the fundamental representation of data?

A.Text characters in the wireless segment and binary digits in the fiber segment.B.Binary sequences (bits) at all stages — represented as radio wave patterns in the wireless segment and as light pulses in the fiber segment.C.Analog signals throughout, since radio waves and light are inherently analog.D.Decimal numbers in the wireless segment converted to binary only when entering the fiber cable.

Question 14

A government proposes using AI-powered surveillance cameras throughout a city to automatically identify and track individuals by face in real time to reduce crime.

A civil liberties advocate argues this innovation has significant harmful effects. Which of the following BEST articulates the advocate's concern?

A.The cameras use too much electricity, making them environmentally harmful.B.Mass real-time facial recognition enables pervasive government surveillance that chills free expression and assembly, disproportionately targets marginalized communities through known algorithmic biases, and creates a massive data collection that could be misused.C.The cameras might reduce tourism because visitors feel uncomfortable being photographed.D.The AI may misidentify celebrities, which could create legal liability for the government.

Question 15

Two programmers are refactoring a 200-line program to reduce code duplication. Programmer A extracts every block of three or more repeated lines into its own procedure. Programmer B extracts only blocks that compute something conceptually meaningful. Which approach is MORE consistent with good procedural abstraction, and why?

A.Programmer A — any duplication should be eliminated, regardless of what the code means.B.Programmer B — procedures are most useful when they have a clear, nameable purpose, even if some duplication remains.C.Programmer A — shorter total code is always better.D.Programmer B — extracted procedures should never have parameters.

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