Data Storage & Compression

Question 1

How many bits are in a byte?

Answer 1

8 bits.

Question 2

How many bytes are in a Kibibyte?

Answer 2

1024 bytes

Question 3

What is the difference between a megabyte and a mebibyte?

Answer 3

A megabyte is 1000 squared bytes, while a mebibyte is 1024 squared bytes.

Question 4

True or False?

When converting between units larger than a byte, we use multiples of 1000.

Answer 4

False.

When converting between units larger than a byte, we use multiples of 1024 (2^10).

Question 5

What is a Tebibyte?

Answer 5

1,099,511,626,776 bytes (2^40 bytes).

Question 6

How do you convert from bytes to bits?

Answer 6

multiply by 8.

Question 7

How do you convert from kibibytes to bytes?

Answer 7

multiply by 1024.

Question 8

What is the formula for calculating the size of a bitmap image?

Answer 8

Resolution x color depth
or
Image width x image height x color depth

Question 9

True or False?

A color depth of 24 bits is equal to 3 bytes.

Answer 9

True.

A color depth of 24 bits is equal to 3 bytes.

Question 10

What is the formula for calculating the size of a sound file?

Answer 10

Sample rate x duration x sample resolution.

Question 11

Define sample rate.

Answer 11

Sample rate is the number of samples taken per second in a digital audio recording.

Question 12

Define sample resolution.

Answer 12

Sample resolution is the number of bits stored per sample in a digital audio recording.

Question 13

How do you convert file size from bits to bytes?

Answer 13

divide by 8

Question 14

How do you convert file size from bytes to kibibytes?

Answer 14

divide by 1024

Question 15

Define compression

Answer 15

Compression is reducing the size of a file so that it takes up less space on secondary storage.

Question 16

State three benefits of compression.

Answer 16

• Less storage space required
• Less bandwidth required
• Shorter transmission time

Question 17

Define lossy compression.

Answer 17

Lossy compression is a method of data compression where data is lost in order to reduce file size, resulting in a loss of quality but smaller file sizes.

Question 18

Define lossless compression.

Answer 18

Lossless compression is a method of data compression where data is encoded to reduce file size without losing any information, allowing the original data to be perfectly reconstructed.

Question 19

True or False?

Lossy compression is reversible.

Answer 19

False.

Lossy compression is irreversible

Question 20

What types of files are suitable for lossy compression?

Answer 20

Files suitable for lossy compression are those where reducing quality is acceptable, such as images, video, and sound files.

Question 21

How does lossy compression work on photographs?

Answer 21

In photographs, lossy compression tries to group similar colours together, reducing the number of colors in the image without significantly compromising the overall visual quality.

Question 22

True or False?

Lossless compression can be used on all types of data

Answer 22

True.

Lossless compression can be used on all types of data.

Question 23

How does lossless compression work on documents?

Answer 23

In documents, lossless compression uses algorithms to analyze the contents, looking for patterns and repetition, such as replacing repeating characters with a single character and the number of occurrences.

Question 24

What is the advantage of lossless compression over lossy compression?

Answer 24

An advantage of lossless compression is that the file can be returned to its original state without any loss of data quality.

Question 25

Describe how lossless compression compresses the text file.

Answer 25

• Compression algorithm is used such as RLE
• Patterns are identified with their position

Question 26

Give two reasons why the text file may have been compressed

Answer 26

• To save storage space
• To make it quicker to transmit