AP CSP Unit 1 Digital Info Study Guide

Which of these values can be stored in a single bit? A. [0, 1] B. 0 C. [2, 4] D. 2

B. 0

Which of the following is a single byte of digital information? A. 1010100111010111 B. 1000 C. 1 D. 01010001 E. 0101100001

D. 01010001

MIK is a character encoding scheme that can encode text written in Bulgarian. MIK uses one byte to encode each character. This binary data is a MIK encoding of a single Bulgarian word: 101101111010000010110001 How many characters are encoded in that binary data?

3

Your programmer friend told you that they just turned 11110 years old, in binary. How old are they in decimal?

30

How many bits are in 4 bytes?

32 bits

You're visiting a Computer Science building at a college, and they've decided it'd be fun to display all the room numbers in binary. You're going to room 13. What binary number should you look for on the door?

1101

Byte pair encoding is a compression algorithm that replaces the most common pairs of characters in a string with a character that isn't in the data, and creates a table of replacement mappings. Which of these words could byte pair encoding compress the most? A. balloons B. zookeeper C. bookkeeper D. ball

C. bookkeeper

3D scanners use projected light to understand the shape of an object and convert it into a 3D point cloud. Each scanner is capable of scanning up to a particular resolution, the minimum distance between two scanned points. This is the lists of resolutions of various 3D scanners: Einscan Pro 2X Plus: 0.2 mm Matter and Form 3D Desktop Scanner: 0.1 mm Freescan Trak: 0.05 mm HDI Compact L6 3D Scanner: 0.08 mm Which of the following comparisons between 3D scanners is the most likely to be true? A. The HDI Compact L6 scanner may miss some details that the Matter and Form scanner captures. B. The HDI Compact L6 scanner will use more bits to represent each point than the Einscan Pro 2X scanner. C. The Freescan Trak scanner will use fewer bits to represent each point than the Matter and Form scanner. D. The Freescan Trak scanner may capture some detail of the object that the Einscan Pro 2X Plus scanner misses.

D. The Freescan Trak scanner may capture some detail of the object that the Einscan Pro 2X Plus scanner misses.

Nuru writes this code to calculate the final cost of an item with a discount applied: price ← 0.7 discount ← 0.2 final ← price - discount They're surprised to see that final stores the value 0.49999999999999994 instead of 0.5. What is the best explanation for that result? A. The result was too large of a number to be stored in floating-point representation. B. An integer overflow error occurred. C. The computer stored the result with floating-point representation instead of integer representation. D. The arithmetic operations on floating-point numbers resulted in a round-off error.

D. The arithmetic operations on floating-point numbers resulted in a round-off error.

Which of the following is a single byte of digital information? A. 10 B. 101011010111 C. 0 D. 1101010 E. 10101101

E. 10101101

Railways have devices called "axle counters" that count up how many train axles have passed by, and helps decide if a train has fully passed part of a track. However, because of a bug in the design of the axle counter logic, a train that has exactly 256 axles will result in a count of 0, and its existence will be ignored. Thus, trains that run on these buggy railways must have less than 256 axles. What is the most likely cause of this bug? A. Limited precision of floating-point numbers B. Integer overflow error C. Incorrect use of integer instead of floating-point representation D. Round-off error in floating-point arithmetic

B. Integer overflow error

Which types of data are stored on a computer using bits? (can be more than one answer) I. Numbers II. Text documents III. Photos

I, II, and III

Categorize each operation as either "lossless" or "lossy": 1. Crop: Trims the sides of the image. 2. Grayscale: Converts the photo to black & white (256 shades of grey). 3. Invert: Inverts all the pixel colors and brightness values (i.e. black pixels become white pixels).

1. lossy 2. lossy 3. lossless

It's your friend's birthday, and you want to use binary numbers for the candles on their cake. Your plan is to use green candles to mean "on" and gray candles to mean "off". What's the least number of candles you need in order to represent the age 18?

5

Which of these lists correctly orders the binary numbers from smallest to largest? A. 0011, 0101, 0110, 1010 B. 1010, 0101, 0110, 0011 C. 1010, 0110, 0101, 0011 D. 0011, 0110, 0101, 1010

A. 0011, 0101, 0110, 1010

Merlin has a file with his favorite wizard spell: ABRACADABRA ALAKAZAM In a standard uncompressed representation, each letter would likely be represented with its ASCII encoding (A as 0100 0001, B as 0100 0010, etc.) The Huffman coding compression algorithm reduces the amount of bits required to represent data by choosing new bit codes for each source symbol, and choosing short codes for the most frequent source symbols. If the computer applies Huffman coding to the wizard spell, which letter is the most likely to be represented with a shorter bit code? A. A B. B C. R D. K

A. A

Huang loves retro songs and discovers a website with audio recordings of many old songs. He's also an animator, so he is inspired to make a video channel with animated music videos for retro songs. Assuming US copyright laws, is Huang allowed to use audio recordings of retro songs for his music videos? A. He can use the audio recordings if they are explicitly licensed for re-use, like with a Creative Commons license, and he follows the conditions of that license. B. He can use the audio recordings as long as he provides attribution, such as an singer name and link back to the site where he found them. C. He can only use the audio recordings if they have been explicitly stated to be in the public domain; he can't use them if they're licensed any other way. D. If there is no explicit license declared next to the audio recordings, then the recordings are in the public domain and can be used freely for any purpose.

A. He can use the audio recordings if they are explicitly licensed for re-use, like with a Creative Commons license, and he follows the conditions of that license.

A musician decides to make a digital recording of their concert so that they can share it with fans that cannot attend the concert in person. What is true about the process of converting the concert's audio waves into a digital recording? A. If the recording equipment uses a very small sampling interval, the digital recording will be a very good representation but will not contain every detail. B. To capture the most amount of details in the digital recording of the concert, the recording process must take samples at the largest interval possible. C. In order for the digital recording to be a more accurate representation of the concert, the recording should use fewer bits to represent each sample. D. As long as the musician purchases a computer with enough storage capacity, the digital recording can record every detail of the original analog data.

A. If the recording equipment uses a very small sampling interval, the digital recording will be a very good representation but will not contain every detail.

Tess is creating an alarm clock using an LCD (liquid-crystal display). Each digit will be 5 pixels wide and 7 pixels tall. She decides to save space by storing the pixels for each digit using run-length encoding (RLE). RLE is a data compression technique that replaces "runs" (sequences of bits with the same value) with a number representing the length of the run. Here's the RLE for one of the digits: 1,3,1 0,1,3,1 0,1,3,1 1,3,1 0,1,3,1 0,1,3,1 1,3,1 In her RLE scheme, the first number in each row represents a run of "off" pixels, the second number represents a run of "on" pixels, and subsequent numbers alternate between representing runs of "off" and "on" pixels. Which digit is represented by that encoding? A. 2 B. 8 C. 5 D. 0 E. 9

B. 8

A software developer is looking for code that they can use to calculate the distance between two points on the Earth's surface. They find a library online called point2point which includes the following license file: Copyright 2019 Nikita Choi Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. What is an implication of this library's open source license? A. The point2point code can be included in any other codebase, and no attribution is required. B. The software engineer is legally allowed to use the code in a software application that they sell to customers. C. The software engineer can use the code, but only if they use it in software that is also licensed under the same open source license. D. The point2point library code is no longer subject to copyright law and is free from copyright restrictions.

B. The software engineer is legally allowed to use the code in a software application that they sell to customers.

Lailah and Alonso are setting up a home security system for their house. The system can currently store 2 months of video on an 8GB hard drive. They are going away for 3 months and want video for all 3 months. What are the best options for them to consider? (2 answers) A. They could put more lights around the camera. B. They could save the videos using a lossy compression algorithm. C. They could save the videos using an inversion filter. D. They could zoom the camera further in. E. They could replace the hard drive with a higher capacity hard drive.

B. They could save the videos using a lossy compression algorithm. E. They could replace the hard drive with a higher capacity hard drive.

Consider a computer that uses 5 bits to represent positive and negative integers, using 1 bit for the sign and 4 bits for the actual value. Which of the following operations would result in integer overflow? (two answers) A. 7 + 1 B. 2 x 4 C. 8 x 2 D. 12 + 3 E. 1 + 15 F. 6 + 9

C. 8 x 2 E. 1 + 15

Compression algorithms vary in how much they can reduce the size of an image. Which of the following would likely be the easiest to compress? A. a colored cartoon of a unicorn B. a photo of a unicorn C. A black & white icon of a unicorn D. A painting of a unicorn

C. A black & white icon of a unicorn

Modern car dashboards contain a number of visual indicators to help drivers be safer, more responsible drivers. Which of these indicators could be represented by a single bit? (two answers) A. the current driving mode (Park/Reverse/Neutral/Drive) B. the fill level of the gas tank (0-40) C. the "ECO" label that indicates the car is in fuel efficiency mode (versus standard fuel mode) D. the temperature in degrees Celsius E. the speed dial (0-160 MPH) F. the warning icon that indicates a seat belt isn't fastened

C. The "ECO" label that indicates the car is in fuel efficiency mode (versus standard fuel mode) F. The warning icon that indicates a seat belt isn't fastened

An Apple Mac computer includes a status menu with various indicators. Which of the indicators could represent a single bit of information? A. The charge level of the battery (0-100%) B. The wireless connectivity level (0-4) C. The bluetooth status (disconnected/connected) D. The current time of day E. The day of the week F. The source of power (battery/adapter)

C. The bluetooth status (disconnected/connected) F. The source of power (battery/adapter)

A programmer is designing a computer program for a weather application that will use a variety of data sources. They want to understand which data sources are analog so that they can think carefully about the process of converting the analog data into digital data. Which of these data sources is analog? A. The predicted inches of snowfall on a winter day for each city in New York B. Two years of weekly high temperatures for Houston, Texas C. Thirty seconds of sounds from a thunderstorm in Miami, Florida D. The daily time of sunrise and sunset in Detroit, Michigan

C. Thirty seconds of sounds from a thunderstorm in Miami, Florida

Consider this sequence of bits: 1000111001011011 0011100010001110 1010101100101111 0110010000010110 1011100011000111 What is true about this binary data? A. This sequence of bits might represent positive numbers and fractional numbers, but it could not represent any negative numbers. B. This sequence of bits might represent positive and negative numbers, but it could not represent any fractional numbers. C. This sequence of bits might represent positive, negative, or fractional numbers. D. This sequence of bits might represent positive numbers, but it could not represent any negative or fractional numbers.

C. This sequence of bits might represent positive, negative, or fractional numbers.

Consider these two files: - A still screenshot of the Apple homepage - A 5-second video of the same Apple homepage Is it possible for the video to take up less space than the image? A. Yes, but only if there is no movement in the video recording of the Apple home page. B. Yes, but only if the video is saved in the Quicktime .mov file format. C. Yes, if the video is compressed with a lossy compression algorithm. D. No, the video will always take up more space than the image.

C. Yes, if the video is compressed with a lossy compression algorithm.

Consider this binary data: 1011011010110001 Which option puts a space after each byte? A. 10 11 01 10 10 11 00 01 B. 1011 0110 1011 0001 C. 1 0 1 1 0 1 1 0 1 0 1 1 0 0 0 1 D. 10110110 10110001

D. 10110110 10110001

How many values can a binary digit store? A. A binary digit can store ten values at a time. B. A binary digit can store one of ten values (0-9). C. A binary digit can store two values at a time. D. A binary digit can store one of two values (0 or 1).

D. A binary digit can store one of two values (0 or 1)

A team of researchers is studying the rate of glaciers melting in the Himalayas over the last three decades and discovers a recent increase in the melting rate. The research team is considering where to publish their research, either in a conventional journal or an open access journal. In terms of access, who would benefit the least from the decision to publish in an open access journal? A. A journalist for a Nepal news site B. A layperson interested in climate change C. A politician in Tibet D. A researcher at a top-tier university

D. A researcher at a top-tier university

Felipe is a videographer that enjoys recording videos of local birds in his free time. Felipe is a big fan of remix culture, so he wants other film-makers to be able to use his recordings but only if they allow their films to be remixed by others. What approach will allow other film-makers to reuse his videos only if they allow reuse of their own remix? A. Felipe should write "Copyright © 2019 Felipe Films" under each of his video recordings. B. Felipe should write "This work is available in the public domain" on each project plan. C. Felipe should link to the MIT open source license under each video recording. D. Felipe should write "This work is licensed under a Creative Commons Attribution ShareAlike license" under each recording.

D. Felipe should write "This work is licensed under a Creative Commons Attribution ShareAlike license" under each recording.

Nora is learning to use image editing applications and doesn't understand when to lower the quality setting for JPEG saving. What's a good use case for using a lower quality setting? A. Saving photos that you want to print out and frame B. Saving a photo of a textbook for easy reading offline C. Saving a photo of a multi-line bar graph with small text labels D. Saving a thumbnail that will link to a full-sized version

D. Saving a thumbnail that will link to a full-sized version

A programmer is writing a software application about birds that will use a variety of data sources. They want to understand which data sources are analog so that they can think carefully about the process of converting the analog data into digital data. Which of these data sources is analog? A. A list of birds that are most commonly seen in a particular park B. The number of reported sightings of a particular bird species in each zip code C. The average length of the songs sung by a particular bird D. The altitude of a bird as it flies through the sky

D. The altitude of a bird as it flies through the sky

A scientist is running a program to calculate the volume of a cone: radius ← 17.24 height ← 5.24 volume ← PI * (radius * radius) * (height / 3) The code relies on the built-in constant PI. After running the code, the variable volume stores 1630.9266447568566. Their supervisor checks their results by running the same calculation on their own computer. Their program results in a volume of 1630.9266447564448. The two values are very close, but not quite the same. Which of these is the most likely explanation for the difference? A. One of the computers has a bug in its mathematical operations. B. One of the computers experienced an integer overflow error when calculating the result. C. The two computers executed the arithmetic operations using a different order of operations. D. The two computers represent the constant PI with a different level of precision, due to their rounding strategy or size limitations. E. One computer used an integer representation for the numbers while the other computer used the more accurate floating-point representation.

D. The two computers represent the constant PI with a different level of precision, due to their rounding strategy or size limitations.