Code.org Unit 1 Digital Information

Which of the following best describes how computing devices represent information?

• A computer will either represent information as bits or bytes but not both

• A computer represents data as a byte which is either a 0 or a 1

• A computer represents data as bits which is either a 0 or a 1

• A computer represents information as bits which contain 8 bytes.

Which of the following is NOT true of how computers represent complex information?

• Computing devices use patterns of bits to represent complex information

• Abstraction helps represent complex information by surfacing complexity that might otherwise be hidden

• Depending on context the same sequence of bits may represent different types of information

• Common abstractions that are represented by computing devices include numbers, characters, and color.

When visiting a museum Lian takes a photo of a painting with a smartphone which stores the photo as an image file. Which of the following best describes the differences between the painting itself and the photo of the painting stored on the smartphone?

• Both the painting and the photo are analog

• The photo is a digital representation of the analog painting

• Sampling can be used to determine whether the analog image is an accurate representation of the painting

• The phone can represent the photo in either digital or analog formats depending on the sampling technique that is used

Your computer uses 4 bits to represent decimal numbers (0, 1, 2, 3 and so on) in binary. What is the SMALLEST number for which an overflow error occur?

• 14

• 15

• 16

• 17

Which of the following is true of how computers represent numbers?

• Using a fixed but large number of bits can eliminate the possibility of round off error when representing numbers in binary

• With a fixed number of bits some numbers are too large to represent in a computer which will lead to overflow errors.

• Using a fixed but large number of bits, for example 128, eliminates the possibility of overflow errors.

• With a large but fixed number of bits it is possible to eliminate either round-off errors or overflow errors, but not both.

Convert the binary (base-2) number 1001 to decimal (base-10).

• 9

• 10

• 16

• 17

Convert the decimal (base-10) number 20 to binary (base-2).

• 10010

• 00101

• 11000

• 10100

Which of the following binary (base-2) numbers is LARGEST?

• 11000000

• 01111111

• 00000001

• 10111111

How many total numbers can be represented with an 8-bit binary (base-2) system?

• 127

• 128

• 255

• 256

Which of the following is true of lossy and lossless compression algorithms?

• Lossy compression algorithms are used when perfect reconstruction of the original data is important.

• Lossy compression algorithms are typically better than lossless compression algorithms at reducing the number of bits needed to represent a piece of data.

• Lossless compression algorithms are only used to compress text data.

• Lossless compression algorithms only allow for an approximate reconstruction of the original data.