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4. Data Compression Online Quiz Questions

Use this free practice quiz with 20 questions to review 4. Data Compression, test your knowledge, and prepare for your next test or exam.

20 questions
01
Choose one
1 point

What is the primary purpose of data compression?

  1. A

    It always encrypts files so that unauthorized users cannot read them.

  2. B

    It represents information with fewer bits than an uncompressed representation.

  3. C

    It guarantees that every file will become exactly half its original size.

  4. D

    It converts all digital files into image files.

02
True or false
1 point

True or false: After lossless decompression, the original data can be reconstructed exactly, bit for bit.

  1. A

    True

  2. B

    False

03
Choose one
1 point

Which representation applies run-length encoding to the sequence AAAAABBB?

  1. A

    A5B3

  2. B

    5A3B

  3. C

    5AB3

  4. D

    A3B5

04
Choose one
1 point

Which situation is an example of temporal redundancy?

  1. A

    Nearby pixels in an image have similar colors.

  2. B

    Some symbols occur more frequently than others.

  3. C

    Consecutive audio or video frames are similar.

  4. D

    A sound is masked by a louder sound.

05
Written response
1 point

A file is reduced from 10 MB to 2 MB. What is the size reduction? Enter the percentage-point value as a number; no tolerance is allowed.

06
Fill in the blank
1 point

When exact recovery of every bit is required, use compression.

07
True or false
1 point

True or false: PNG filters themselves reduce the number of bytes in the image before DEFLATE is applied.

  1. A

    True

  2. B

    False

08
Choose one
1 point

Which technique exploits statistical redundancy by assigning shorter codes to more frequent symbols?

  1. A

    Huffman coding

  2. B

    Run-length encoding

  3. C

    Quantization

  4. D

    Temporal prediction

09
Choose all
1 point

Select all data types for which lossless compression is appropriate because changes may be unacceptable.

  1. A

    Source code and executable programs

  2. B

    Legal, financial, or scientific records

  3. C

    Photographs displayed on websites

  4. D

    Spreadsheets and databases

10
Written response
1 point

What is the technical term for reducing precision in image data as part of a lossy compression process? Enter the term in lowercase.

11
Fill in the blank
1 point

Lossy compression produces an of the original data rather than an identical copy.

12
Choose all
1 point

Select all factors that should be considered when selecting an appropriate compression method.

  1. A

    Whether exact recovery is required

  2. B

    The type of data being compressed

  3. C

    Acceptable quality and quality settings

  4. D

    Compatibility and preservation requirements

13
Choose one
1 point

A diagram contains sharp text, flat colors, and transparency. Which choice is most appropriate for rapid delivery while preserving those features?

  1. A

    Choose JPEG because it always preserves every pixel exactly.

  2. B

    Choose PNG because the diagram has sharp text, flat colors, and transparency.

  3. C

    Choose a lossy format because diagrams cannot be compressed losslessly.

  4. D

    Choose ZIP alone because image formats cannot use compression.

14
Open ended
1 point

A team must compress both a spreadsheet that will be edited later and a video that will be streamed over a limited-bandwidth connection. Recommend a compression approach for each and explain how quality, file size, and usability affect the choices.

15
Choose one
1 point

A 10 MB file is compressed to 2 MB. What is its compression ratio?

  1. A

    2:1

  2. B

    4:1

  3. C

    5:1

  4. D

    8:1

16
Choose one
1 point

A financial spreadsheet must be compressed for storage, and every cell must be recovered exactly after decompression. Which approach is most appropriate?

  1. A

    Lossy compression, because spreadsheets contain repeated values

  2. B

    Lossless compression, because every cell must be preserved exactly

  3. C

    Lossy compression, because smaller files are always preferable

  4. D

    No compression, because structured data cannot be compressed

17
True or false
1 point

True or false: In PNG, filtering is reversible preprocessing that can make data easier to compress, but the filters themselves do not reduce the number of bytes.

  1. A

    True

  2. B

    False

18
Choose one
1 point

A designer needs to publish a diagram containing sharp text, flat colors, and transparent regions. Which format is the better choice according to the material?

  1. A

    JPEG, because it always preserves sharp text better than PNG

  2. B

    JPEG, because transparency requires lossy compression

  3. C

    PNG, because it is well suited to sharp text, flat colors, and transparency

  4. D

    Either format, because their compression behavior is identical

19
Written response
1 point

A file is reduced from 10 MB to 2 MB. What is its compression ratio? Enter the ratio as original size divided by compressed size; enter the number only.

20
Written response
1 point

A file is reduced from 50 MB to 35 MB. What is the size reduction? Enter the percentage-point value as a number only; the fixed unit is %.