AP CSP - Digital Info Review

What is the 4-bit binary number for the decimal number Ten (10)?

• 0010

• 1010

• 0110

• 0101

What is the minimum number of bits you would need to encode the 26 letters of the alphabet plus a space - a total of 27 characters?

• 2 bits

• 3 bits

• 5 bits

• 6 bits

What is the best explanation for why digital data is represented in computers in binary?

• The binary number system is the only system flexible enough to allow for representing data other than numbers.

• It's easier, cheaper, and more reliable to build machines and devices that only have to distinguish between binary states.

• It typically takes fewer digits to represent a number in binary when compared to other number systems (for example, the decimal number system)

• It's impossible to build a computing machine that uses anything but binary to represent numbers

Number systems with different bases such as binary (base-2) and decimal (base-10) are all used to view and represent digital data. Which of the following is NOT true about representing digital data?

• At one of the lowest levels of abstraction, all digital data can be represented in binary using only combinations of the digits zero and one.

• The same value (number) can have a different representation depending on the number system used to represent it.

• Groups of bits can be used to represent abstractions, including but not limited to numbers and characters.

• Some large numbers cannot be represented in binary and can only be represented in decimal.

Which of the following is the greatest binary value?

• 00001000

• 00010000

• 00001111

• 00010001

8 bits is enough to represent 256 different numbers. How many total bits do you need to represent 512 (twice as many) numbers?

• 9 bits

• 10 bits

• 16 bits

• 17 bits

Two students have developed a protocol in which they send 4-bit messages to each other. They decide to modify their protocol to start sending 8-bit messages instead. How many more values can be represented in an 8-bit message than a 4-bit message?

• 2¹ = 2 times as many values

• 2² = 4 times as many values

• 2³ = 8 times as many values

• 2⁴ = 16 times as many values

Under which of the following conditions is it most beneficial to use a heuristic approach, not an algorithm, to solve a problem?

• When the problem can be solved in a reasonable time and an approximate solution is acceptable

• When the problem can be solved in a reasonable time and an exact solution is needed

• When the problem cannot be solved in a reasonable time and an approximate solution is acceptable

• When the problem cannot be solved in a reasonable time and an exact solution is needed

The colors of the pixels in a digital image are often represented by red, green, and blue values between 0 and 255 (an RGB triplet). A photographer is manipulating a digital image to lighten it because all of the RGB values in the image are less than 100, making it very dark. He does this by adding 20 to the R, G, and B values of each pixel, then overwriting the original image. What type of transformation is the photographer using on the digital image?

• Lossless transformation

• Lossy transformation

• Both of these

• Neither of these

Which of the following lists the units of bytes in ascending order (from smallest to largest)

• gigabyte, megabyte, terabyte

• megabyte, terabyte, kilobyte

• gigabyte, terabyte, megabyte

• kilobyte, gigabyte, terabyte