AP CSP Practice Test Parallel Computing

AP CSP Test 4.2: Parallel & Distributed Computing

Sequential vs. parallel processing, speedup, distributed systems, and scalability

25 Questions ~30 Minutes Instant Scoring
Question 1 Sequential vs Parallel
A program must perform four independent tasks: A (2 sec), B (4 sec), C (3 sec), and D (1 sec). If all tasks run sequentially on a single processor, how long does the program take?
Question 2 Parallel Speedup
Using the same four tasks from Question 1 (A=2s, B=4s, C=3s, D=1s), if the program uses four processors to run all tasks simultaneously, what is the minimum execution time?
Question 3 Parallel Speedup
A sequential program takes 60 seconds. When parallelized across 4 processors, it finishes in 20 seconds. What is the speedup?
Question 4 Limitations
A program has two phases: Phase 1 (10 seconds, must run on one processor) and Phase 2 (40 seconds of work, perfectly divisible among processors). With 4 processors, what is the total execution time?
Question 5 Sequential vs Parallel
Which of the following tasks would benefit LEAST from parallel processing?
Question 6 Distributed Computing
A distributed computing project uses thousands of volunteers’ home computers to analyze radio telescope data. Which of the following BEST describes why distributed computing is used for this task?
Question 7 Parallel Speedup
A task takes 120 seconds on one processor. With 2 processors, it takes 65 seconds. Which statement BEST explains why the speedup is less than 2x?
Question 8 Distributed Computing
Consider the following statements about distributed computing:

I. Distributed computing can combine the processing power of many computers across the Internet.
II. Distributed systems never experience communication delays between computers.
III. Distributed computing allows problems to be solved that are too large for a single computer.

Which statements are true?
Question 9 Parallel Speedup
Six independent tasks each take 5 seconds. A system has 3 processors. What is the minimum total execution time if tasks are distributed evenly?
Question 10 Sequential vs Parallel
A program processes steps A, B, C, and D. Step B requires the output of step A. Step C requires the output of step B. Step D is independent of all other steps. Which of the following correctly identifies what can run in parallel?
Question 11 Limitations
Doubling the number of processors from 4 to 8 reduces a program’s execution time from 30 seconds to 25 seconds. What is the MOST likely explanation?
Question 12 Parallel Speedup
Three tasks have the following dependencies: Task X (6 sec, no dependencies), Task Y (4 sec, depends on X), Task Z (8 sec, no dependencies). With 2 processors, what is the minimum execution time?
Question 13 Distributed Computing
A company uses cloud computing to handle increased web traffic during a product launch. This is an example of:
Question 14 Sequential vs Parallel
A sorting algorithm requires comparing and swapping elements, where each comparison depends on the current arrangement. This type of algorithm is BEST described as:
Question 15 Parallel Speedup
A program has 80% of its work parallelizable and 20% that must run sequentially. With an infinite number of processors, what is the maximum possible speedup?
Question 16 Distributed Computing
Which of the following is a challenge unique to distributed computing that does NOT apply to parallel computing on a single machine?
Question 17 Parallel Speedup
Eight identical tasks each take 12 seconds. A system has 3 processors. What is the minimum execution time?
Question 18 Sequential vs Parallel
Which of the following real-world scenarios is MOST analogous to parallel computing?
Question 19 Limitations
A programmer parallelizes a program and finds that adding processors beyond 8 provides almost no additional speedup. Which of the following is the MOST likely reason?
Question 20 Distributed Computing
A weather prediction system divides the Earth into grid cells and assigns each cell’s calculations to different computers. This approach is used because:
Question 21 Parallel Speedup
Tasks P (3s), Q (3s), R (3s), S (3s), and T (3s) are all independent. With 2 processors, what is the minimum execution time?
Question 22 Limitations
Consider the following statements about parallel computing:

I. Adding more processors always makes a program run faster.
II. Some problems contain portions that must be executed sequentially.
III. Communication between processors adds overhead that can reduce efficiency.

Which statements are true?
Question 23 Parallel Speedup
A program takes 100 seconds sequentially and 28 seconds with 4 processors. What is the approximate speedup?
Question 24 Distributed Computing
A blockchain network uses thousands of computers worldwide to validate transactions. If several computers go offline, the network continues to function. This demonstrates:
Question 25 Parallel Speedup
A rendering job splits 24 frames across processors. Each frame takes 5 seconds to render. How many processors are needed to complete the job in exactly 30 seconds?
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out of 25

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Answer Review

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