Brian V. Computer Science - Digital Information, The Internet, and Algorithms Study Guide

The United States Postal Service (USPS) delivers nearly 200 million pieces of mail every day. Their website and internal operations are powered by many algorithms. Which algorithm's runtime is most likely to be improved by the use of a heuristic? (Algorithms)

Calculating an efficient route for a delivery carrier through a city, considering factors like parking space and mail volume

In the Internet Protocol (IP), computers send messages to each other through a network of routers, with each message split up into packets. How do routers determine where a packet needs to go? (The Internet)

Routers look at the IP packet header and use the destination address field.

How many bits are in 4 bytes? (Digital Information)

32 bits

Audacity is an open source audio editing application that provides a variety of effects that you can apply to audio files. Which of these effects sounds like a lossy operation? (Digital Information)

Equalization: Adjusts the volume levels of particular frequencies.

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? (Digital Information)

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.

Many people worry about what would happen if either the Internet or the World Wide Web went down (if they suffered a complete outage and were unreachable). Which of these predictions is correct? (The Internet)

If the Internet went down, the World Wide Web would also go down, since the WWW relies on the Internet protocols.

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? (Digital Information)

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.

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? (Digital Information)

Integer overflow error

Amazon describes their web services platform like this: Amazon Web Services (AWS) is a highly reliable, scalable, low-cost infrastructure platform in the cloud that powers hundreds of thousands of enterprise, start-up and public sector business with organizations in over 190 countries around the world. What does it mean for the platform to be scalable? (The Internet)

It continues operating when experiencing traffic surges.

In what situations is the Internet Protocol (IP) used? (The Internet)

It is used every time that two computing devices send data to each other over the Internet.

Rafi is developing an application to send urgent information about global health crises over the Internet to hospitals. He is worried about packets getting lost along the way and the effect that will have on the accuracy of the information. What is his best option for dealing with lost packets? (The Internet)

Rafi can use the Transmission Control Protocol for communication, since TCP has ways to recover when packets are lost.

The following algorithm computes the maximum score for a list of final exam scores. Initialize a variable max to the first score in the list. For each score in the list, compare the score to max. If score is greater than max, store score in max Return max. Which building blocks are involved in this algorithm? (Algorithms)

Selection, Iteration, and Sequencing

What example of what digital divide can do (The Internet)

The digital divide is affected by geography; some areas are harder to connect to the Internet than others.

Consider these files: A 3-second audio recording of a baby's first word. A 30-second video recording of a baby's first steps. Is it possible for the 30-second video recording to have a smaller file size than the 3-second audio recording? (Digital Information)

Yes, if the 30-second video is compressed with a lossy compression algorithm.

A computer must adhere to the Internet protocols in order to send data through the Internet. Which of these best describe what it means for a computer to adhere to a protocol? (The Internet)

The computer must send data according to the documented rules of the protocol.

How many values can a binary digit store? (Digital Information)

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

Which of these situations describes the creation of a computer network? (The Internet)

A college campus creates multiple computer labs in different parts of the campus and connects the labs to each other with underground fiber optic cables. Students can save their file on a computer in one lab and still access their files from another lab.

Which of the following is the best description of parallel computing? (Algorithms)

A computational model in which a program is broken into smaller subproblems, some of which are executed simultaneously.

Your classmate constructs a simple computer that adds numbers. There are 5 wires for inputting the first number, and the wires are currently "on", "on", "off, "on", "off", or 110101101011010 in binary. What decimal number does that represent? (Digital Information)

26

A programmer working for the US government is tasked with writing a program to detect fraudulent voter registration. The programmer tries to run the program on their work computer and realizes the computer is too slow to process all of the voter registration records in time for the next election. They decide to use distributed computing to improve the performance. How could a distributed computing solution help? (Algorithms)

A distributed computing solution can analyze multiple registration records at once by using multiple computers.

Which types of data are stored on a computer using bits? Whole numbers .Fractional numbers Text files (Digital Information)

All three

An algorithm will be used to calculate the difference between the smallest and largest values in a list. For the list of [10, 3, 5, 6], it should calculate a difference of 7. There are two proposals for the algorithm: Algorithm 1: Set minVal to the first value in the list and maxVal to the last value in the list. Iterate through each number in the list. If the number is greater than maxVal, store it in maxVal. If the number is less than minVal, store it in minVal. After loop, set maxDiff to the difference between maxVal and minVal. Algorithm 2: Set minVal to 1000 and maxVal to 0. Iterate through each number in the list. If the number is greater than maxVal, store it in maxVal. If the number is less than minVal, store it in minVal. After loop, set maxDiff to the difference between maxVal and minVal. Which of these statements are true about these algorithms? I. Algorithm 1 does not work on lists where the smallest value is at the start of the list or the largest value is at the end of the list. II. Algorithm 2 does not work on lists that contain all negative numbers or all numbers over 1000. (Algorithms)

II Only

Serena operates a security camera that stores still images in timestamped filenames. The camera can generate thousands of images each day, and she needs a way to find the image corresponding to a particular timestamp. She comes up with this algorithm: Start with a list of the image filenames, sorted from oldest to newest. Set min to 1 and max to the number of images. Set index to the average of max and min, rounded down so that it is an integer. Check the filename located at that index in the list. If the filename equals the desired timestamp, the search is done! Exit the algorithm. If the filename is older than the desired timestamp, set min to be one larger than index. If the filename is newer than the desired timestamp, set max to be one smaller than index. Go back to step 3. Which statements are true about this algorithm? (Algorithms)

It implements a binary search and It is more efficient than a linear search.