AP Computer Science Principles Unit 3 Review

ASCII is a character-encoding scheme that uses a numeric value to represent each character. For example, the uppercase letter “G” is represented by the decimal (base 10) value 71. A partial list of characters and their corresponding ASCII values are shown in the table above.

ASCII characters can also be represented by binary numbers. According to ASCII character encoding, which of the following letters is represented by the binary (base 2) number 1010100?

• N

• P

• T

• W

Which of the following decimal (base-10) values is equivalent to the binary (base-2) value 101001?

• 22

• 37

• 41

• 82

What value does the above code segment display?

• 17

• 36

• 53

• No value is ever displayed because the algorithm repeats the REPEAT UNTIL block indefinitely.

Remember that “state space” refers to the space of all potential possibilities. Which dichotomous questions below will successfully narrow down the entire state space of “flipping a coin and rolling a normal six-sided die” to just 1 outcome?

• Did the coin land on tails?

  Is the value on the die less than 3?

  Is the value on the die even?

  Is the value on the die 4, 5 or 6?

• Is the value on the die even?

  Did the coin land on heads?

  When the value on the die is multiplied by 4, is it even?

  Does the value on the die equal 1, 2 or 3?

• Did the coin land on heads?

  Is the value on the die odd?

  Is the value on the die more than 3?

  Does the value on the die equal 1, 2, 5 or 6?

• None of these will narrow down the state space to just one outcome

As of 2016, the selling of used digital media is illegal. Along with selling it, there are many other illegal uses of digital media. Which of the following would be a legal use of digital media?

• You download an app on your smartphone that allows you to ‘strip’ the audio from any YouTube music video and permanently keep that audio in your music collection.

• You make an MP3 copy of a song because the CD you bought expressly permits you to do so, and then you put your MP3 copy on the Internet, using a file-sharing network, so that millions of other people can download it.

• You have a computer with a CD burner, which you use to burn copies of music you have downloaded onto writable CDs for all of your friends.

• You download a song from iTunes and sync it to the cloud so that it is accessible on all of your devices.

The above procedure check is called in a program after each time a True or False question is answered. If the user types in True True False True as their answers for four questions on a quiz, what should their overall score be?

• 25%

• 50%

• 75%

• 100%

ASCII is a character-encoding scheme that uses 7 bits (8 bits if you are using the extended ASCII table) to represent each character. The decimal (base 10) values 65 through 90 represent the capital letters A through Z, as shown in the table above.

Which ASCII character is represented by the binary (base 2) number 1000001?

• A

• B

• C

• D

Sort the following numbers, that are written in different bases, in numerical order from smallest to largest:

2548 AE16 101011012

• 
• 
• 
• 

Which statements below are true about fixed and variable width encoding?

Select two answers.

• Variable width encoding must use some sort of delimiter in order to designate where one character stops and another begins.

• Variable width encodings will always be longer than a fixed width encoding.

• Fixed width encodings are limited to only 8 bits of data.

• Fixed width encodings are typically longer than variable width encodings.

Which of the following decimal values, when converted to binary (ignore leading zeros) have exactly 3 zeros in them?

Select two answers.

• 20

• 30

• 40

• 50