Study Guide -Review Week 1

Consider these two files: -A 1-minute video of a cat pouncing ferociously on a twisty tie. -A download of "The Lion King", a 1.5-hour animated film Is it possible for "The Lion King" to have a smaller file size than the shorter cat video?

Yes, if "The Lion King" video is compressed with a lossy compression algorithm.

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 round off error occurred

Which of these lists correctly counts from 1 to 5 in binary?

00010001, 001000100010, 001100110011, 010001000100, 01010101

In what situations does a computer use multiple Internet protocols to send a message? 1) When it sends an encrypted message 2) When it wants an acknowledgment that the destination computer received the message 3) When it is loading webpage data

1,2, & 3

Josiah used a tool to measure how many bits he could transfer over his home connection to the Internet. This table shows the bits transferred each second: seconds Bits transferred 1 900 2 800 3 700 4 1100 5 800 According to those measurements, what is the bandwidth of the connection?

1100 bits/s

Consider this sequence of bits: 1011001010010010 How many bytes long is that sequence of bits?

2

TSCII is a character encoding scheme that can encode text written in the Tamil language. TSCII uses one byte to encode each character. This binary data is a TSCII encoding of a single Tamil word: 11111110110001001100010110111010 How many characters are encoded in that binary data?

4

Run-length encoding (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. This is an RLE encoding for an 8x8 black & white icon: 8 1,2,2,2,1 1,2,2,2,1 8 8 2,4,2 1,1,4,1,1 8 In this RLE scheme, the numbers represent alternating runs of black and white pixels and the first number in each line represents a run of white pixels.

:( A frowning face

What values can a binary digit represent?

A binary digit can represent either the value 0 or 1.

Which of the following best illustrates inequity caused by the digital divide?

A community college student does their homework in the waiting room of a local hospital because they don't have Wi-Fi at home.

A programmer is writing the code for a sports website 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 swimmer's position in the pool as they swim from one end to the other

The two algorithms below are both intended to calculate the sum of squares from 1 to n, where n is any positive integer. For example, if n is 333, the algorithms should calculate a sum of 14, from 1^2 + 2^2 + 3^2. Algorithm 1: i ← 1 sum ← 0 REPEAT n TIMES { sum ← sum + (i * i) i ← i + 1 } Algorithm 2: i ← 1 sum ← 0 REPEAT n TIMES { sum ← sum + (i + i) i ← i + 1 } Which statements best describe the behavior of the algorithms?

Algorithm 1 calculates the correct sum, but algorithm 2 does not

Which of these is an accurate description of how the TCP/IP protocols send data around the internet?

Computers split messages into packets and send them through routers to their final destination. The destination computer acknowledges the receipt of each packet, so that the sending computer can ensure every packet is delivered.

The IPv6 protocol is the most recent version of the Internet Protocol (IP). IPv6 includes several new features related to both addressing and routing. Which of the following features of IPv6 most directly increases the scalability of the Internet?

Each IPv6 address is a 128-bit number. That means there are 2^128(3.4 * 10^38) possible addresses for Internet-connected computing devices.

Which statement is true about computing devices in a computer network?

Each computing device must be able to send data to the other computing devices.

When packets are routed on the Internet, the route for a particular packet is not pre-determined. Instead, the next hop is decided by each router along the way. How does that increase the fault tolerance of routing on the Internet?

Each router can pick a connection that's currently working and available.

A programmer wants to present their idea for an algorithm at a company meeting. They're debating whether to express the algorithm in flow charts, pseudocode, or a programming language. Which of these is a good argument for expressing the algorithm in a flow chart at the company meeting?

Flow charts can require less technical knowledge to understand than pseudocode or programming languages.

An algorithm will be used to decide whether every number in a list is either a 4 or a 5. There are two proposals for the algorithm: Algorithm 1: Set only45 to false. Iterate through each number in the list. If the number is not equal to 4 and not equal to 5, set only45 to false. Otherwise, set only45 to true. Algorithm 2: Set only45 to true. Iterate through each number in the list. If the number is not equal to 4 and not equal to 5, set only45 to false. Which of these statements are true about these algorithms? I. Algorithm 1 does not work on lists where a number other than 4 and 5 occurs before the last number. II. Algorithm 2 does not work on lists which contain entirely 4s or entirely 5s.

I only

Han develops an algorithm to compute the average amount of time that users watch a particular video on Khan Academy. He then realizes that the average is very low, due to a large number of times with duration "0" or "1", and decides that the algorithm should ignore those durations. What structure must be added to the algorithm so that it does not consider those short durations when computing the average?

Selection

Why does each IP packet contain a destination address?

Routers use the destination address to decide where to send a packet next.

What is the relationship between the Internet and the World Wide Web?

The World Wide Web is built on top of the Internet.

A security engineer is developing antivirus software that detects when downloaded programs look similar to known viruses. They would like the software to be able to detect viruses that it's never seen before, by predicting whether or not a program will ever execute malicious code. After a bit of research, the engineer realizes that virus detection is an undecidable problem. What are the consequences of the problem being undecidable?

The engineer might come up with an algorithm that correctly predicts the execution of malicious code in some cases, but the algorithm will not be correct all of the time.

A mathematician develops a program to solve systems of linear equations. When they use distributed computing techniques to run the program on two computers in parallel, they find a speedup of 2.

The program completed in half the time with two computers versus one computer.

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?

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

Which of the following statements about IP addresses is true?

When data is sent between devices on the Internet, they identify each other with an IP address.

Dylan is creating graphics for a mobile app, and he wants his images to take up a small amount of space. Help him decide what kind of images to make.

When it comes to image type, computers can more easily compress: digital clip art: Digital clip art The best color palette for compression is: Black and White

Which of these situations is most analogous to parallel computing?

When multiple people work on a jigsaw puzzle, they can each work on a different part of the puzzle. Once each person has put together a significant area of the puzzle, they can merge the areas and see the completed puzzle.

The following passage describes the Internet but contains a missing adjective: The Internet is built on a stack of communication protocols that are standardized and <???> . As a result, any computer can communicate with other computers on the Internet, without needing to apply for a license from a company. What is the most appropriate adjective to replace <???>?

nonproprietary