2020 Practice Exam 1 MCQ

When I took the 2020 Practice Exam 1 MCQ, I achieved a score of 44/67, of which I’m not super proud of, however I must correct my mistakes in order to learn from them and prepare for the AP exam coming up on the horizon. As my score of 44 is under 55, I must reflect and take note of went well and what didn’t go so well on each question I missed. While looking over my score and thinking back to how the exam felt as I was taking it, it felt as though the questions got harder as time progressed and, especially toward the end, the questions starting taking longer and longer to come up with an answer.

Test Corrections

Q4: Cause of overflow error

  • In a certain computer program, two positive integers are added together, resulting in an overflow error. Which of the following best explains why the error occurs?

The answer would be because the sum of the two integers is too large to be displayed with the current computer’s number of bits.

Q9: Transmit private data securely

  • An Internet user has a need to send private data to another user. Which of the following provides the most security when transmitting private data?

I got this answer wrong as a Creative Commons liscense has nothing to do with the security of transmitting private data, rather, who can use certain software. However, when transmitting private data, using a public-key would offer you the most security while encrypting

Q12: Binary representation of indigo

  • A color in a computing application is represented by an RGB triplet that describes the amount of red, green, and blue, respectively, used to create the desired color. A selection of colors and their corresponding RGB triplets are shown in the following table. Each value is represented in decimal (base 10). What is the binary RGB triplet for the color indigo?

I arrived at my answer of (00100101, 00000000, 10000010) by using processes of elimination, but miscalculated the binary code itself by one figure. All this is is a simple arithmetic error that could’ve easily been avoided with more binary understanding, as well as more attention when filling out the exam

Q13: Information determined by library system

  • A library system contains information for each book that was borrowed. Each time a person borrows or returns a book from the library, the following information is recorded in a database. Which of the following CANNOT be determined from the information collected by the system?

I said that the number of books returned past their due date cannot be determined, but this can easily be determined by comparing each book’s return with when they were due to be returned. However, the number of books that were never borrowed cannot be determined, as we don’t know the capacity of the library and the count of books in stock.

Q15: Compare output of program a and b

  • Consider the two programs below. Which of the following best compares the values displayed by programs A and B?

I had originally thought that the two programs would display different values due to their different composition and variable ‘i’, however the fact that program II was a flip flop of program I meant that the displayed values stayed the same, no matter what ‘i’ was originally set to.

Q16: Error in wordlist traversal

  • A student wrote the following program to remove all occurrences of the strings “the” and “a” from the list wordList. While debugging the program, the student realizes that the loop never terminates. Which of the following changes can be made so that the program works as intended?

My selection between lines 7 and 8 incriments the index each time, however the loop is checking for the index to be less than 1, so I must make the index incriment downward between lines 7 and 8 to make the index approach 0.

Q17: Data represented by bit sequences:

  • Which of the following can be represented by a sequence of bits?

My selection of an integer and an alphanumeric integer ONLY is incorrect as quite literally anything on the computer can be and is represented by a sequence of bits for the computer to understand, including, and especially, that of a machine language instruction.

Q20: Average amount of data per user

  • A file storage application allows users to save their files on cloud servers. A group of researchers gathered user data for the first eight years of the application’s existence. Some of the data are summarized in the following graphs. The line graph on the left shows the number of registered users each year. The line graph on the right shows the total amount of data stored by all users each year. The circle graph shows the distribution of file sizes currently stored by all users. Which of the following best describes the average amount of data stored per user for the first eight years of the application’s existence?

I only payed attention to the graph of the total amount of data stored by the company and failed to take into consideration the amount of people that signed up to use this storage software over the sample period of 8 years. When you compare both graphs, you realize that the amount of data stored and the amount of active users both grow at a steady linear rate, meaning that the amount stored per person is going to be an unchanging amount. to calculate roughly how much each person stores, we can take a look at the first data point. With 26 million people storing a total of 262 million GB, 262/26 ~ 10 GB per person over the span of 8 years.

Q21: File size distribution

  • A file storage application allows users to save their files on cloud servers. A group of researchers gathered user data for the first eight years of the application’s existence. Some of the data are summarized in the following graphs. The line graph on the left shows the number of registered users each year. The line graph on the right shows the total amount of data stored by all users each year. The circle graph shows the distribution of file sizes currently stored by all users. Which of the following observations is most consistent with the information in the circle graph?

There are a lot of files stored above 100 KG, but this only accounts of 34% of the total data stored. A careful observation of the pie chart will reveal that a much larger portion of the files stored are less than 10 MB, or 76% of them.

Q24: Count by twos 10 times

  • Consider the following program. Which of the following describes the result of executing the program?

Because the algorithm is incrimenting by 2 each time and is set to repeat 10 times, it’ll add up to a sum of 20 when terminated, only counting the even numbers. However, I thought that, for some unknown reason at the time, it would only add up to 10 and then terminate, while only adding the even numbers.

Q26: Metadata for an image

  • A list of binary values (0 or 1) is used to represent a black-and-white image. Which of the following is LEAST likely to be stored as metadata associated with the image

Metadata being the data of, or to support, data, means that copyright information is important and should be stores as information about the image. However, a duplicate of the data is deemed unnecessary and wont be kept alongside the rest of the data for the image.

Q29: Lossless compression scenario

  • A person wants to transmit an audio file from a device to a second device. Which of the following scenarios best demonstrates the use of lossless compression of the original file?

Taking out details that cannot be perceived by the human ear is still considered unlossless, as you are losing details, however if you compress the file but decompress it on the receiving end, you aren’t losing any data and the file will be restored to its normal state.

Q32: Calculate course grade

  • A student’s overall course grade in a certain class is based on the student’s scores on individual assignments. The course grade is calculated by dropping the student’s lowest individual assignment score and averaging the remaining scores. For example, if a particular student has individual assignment scores of 85, 75, 90, and 95, the lowest score (75) is dropped. The calculated course grade is (85 + 90 + 95)/3 = 90. A programmer is writing a program to calculate a student’s course grade using the process described. The programmer has the following procedures available. The student’s individual assignment scores are stored in the list scores. Which of the following can be used to calculate a student’s course grade and store the result in the variable finalGrade?

For this problem, I just forgot to take into consideration the fact that we are dropping the lowest test score, so the average is gonna include one less test score. Therefore, when dividing the final grade by the length of the list, we are using the new list without the lowest score, so we must subtract one from the length of the original list.

Q38: Benefit of IPv6

  • Internet protocol version 6 (IPv6) has been introduced to replace the previous version (IPv4). Which of the following best describes a benefit of IPv6 over IPv4?

My answer just came from a lack of knowledge of the different versions of IP and how they differ from each other. I had thought that the updated version would be faaster based on my intuition, as that is a pretty important thing when it comes to optimizing technology, however this was not the case. This new update IP allows for more addresses, which means more accessibility for divices to connect to the internet at once.

Q39: Error in calculating sum

  • Assume that the list of numbers nums has more than 10 elements. The program below is intended to compute and display the sum of the first 10 elements of nums. Which change, if any, is needed for the program to work as intended?

At first glance, I thought that this program ran normally and that no lines needed to be interchanged because it ran as intended when I ran through it in my head. However, as incrimenting ‘i’ before calculating the sum doesn’t include the first value in the actual sum, which would make the program run inproperly. So interchanging the 5th and 6th lines would fix this issue.

Q48: Phishing scenario

  • Which of the following scenarios best exemplifies a phishing attack?

At first I couldn’t remember what a phishing attack was, but a quick google search reminded me that the attack is an attempt to steal account and personal info to sell or use for malicious reasons. Based on this short description, I concluded that the example of an unauthorized person guessing the password of a user and obtaining access to their account would be the best example of this however I was mistaken. A phishing attack requires the user to be tricked into giving away valuable personal information, so an email that asks for a user’s username and password with malicious intent would be considered a phishing attack.

Q49: Unique bit sequences for staff

  • An office uses an application to assign work to its staff members. The application uses a binary sequence to represent each of 100 staff members. What is the minimum number of bits needed to assign a unique bit sequence to each staff member?

This was very simply an error of binary calculation, very similar to that of the color problem. I had forgotten that you can reach every number up to what 2 to the power of the number of digets there are is. Meaning that with 7 bits, you can assign work to 2^7 or 127 different staff members minimum.

Q50: Reasonable time algorithms

  • Consider the following algorithms. Each algorithm operates on a list containing n elements, where n is a very large integer. Which of the algorithms run in reasonable time?

When I arrived to this problem, I had no idea what it meant by ‘reasonable time’, as programs usually run almost instantly when running small programs, but I chose the first example as it was the least complext. However, all three were as time efficient, because they are all considered “reasonable time”

Q55: Average height algorithm

  • The following algorithm is intended to determine the average height, in centimeters, of a group of people in a room. Each person has a card, a pencil, and an eraser. Step 2 of the algorithm is missing. Which of the following can be used as step 2 so that the algorithm works as intended?

This was what I consider a stupid mistake. I knew that the smaller number should’ve been on the bottom to calculate the average, so I picked the wrong answer. In the future, I should double check my answer choice and reread both the question and my selected response before committing.

Q59: Advantages of open source software

  • Which of the following is NOT an advantage of using open-source software?

I don’t have much personal experience using open-source software so I can be considered “not the guy to ask” when it comes to this kind of stuff. That being said, I felt that the software being able to constantly be updated without the intervention of the creator wasn’t the biggest advantage as the user themselves can alter it to their needs anyway. However, the author provides supportive software cannot be an advantage as the open-source software can still be used without it.

Q62: Which selection statements will display true

  • Assume that the Boolean variable x is assigned the value true and the Boolean variable y is assigned the value false. Which of the following will display the value true ? Select two answers.

For my selection, I failed to realize that it was a 50/50 of being true. However, if only x is taken into consideration, then the evaluation must always come out to true.

Q66: Error in counting perfect numbers

  • In mathematics, a perfect number is a type of integer. The procedure IsPerfect (num) returns true if num is a perfect number and returns false otherwise. The following program is intended to count and display the number of perfect numbers between the integers start and end, inclusive. Assume that start is less than end. The program does not work as intended. Which two lines of code should be removed so that the program will work as intended?

I said line 8 and line 11 because they both already happen previously in the code, without realizing that the sequence of the code matters. The variable should only increase if the number is a perfect number, so it must be a part of the if statement. Every integer should be checked, so the checker should be removed from inside the if statement.

Q67: Error in numOccurrences procedure

  • The procedure NumOccurrences is intended to count and return the number of times targetWord appears in the list wordList. The procedure does not work as intended. For which of the following code segments will the call to NumOccurrences NOT return the intended value?

I just failed to realize that ‘spruce’ would givve you a 0 as it is not in the segment and works as intended, however the checker resets after each check, so its check of maple in the middle would return 0 once it determines that oak doesnt equal maple, deeming an incorrect result.

Closing thoughts

As I reflect and correct all my mistakes, I’ve noticed 2 major things in particular. My main mistake is just a misreading or lack of proofreading of my response and a lack of checking to make sure its proper, especially on the pseudocode problems. My other major mistake is just a simple blantant lack of knowledge of a specific term or action, which causes me to have a skeweed perception of what it means, and to misinterpret the situation. All in all, this exam was fun to take and has showed me my position as I prepare for the AP exam. Im aware that I have lots of progress to make and I will try my hardest to do so to prepare myself the best that I possibly can for the AP exam.