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04 - Data Capacity and Calculating Storage

 1. How many bits are there per character? 
Given the below what would your answer be?
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An ASCII character in 8-bit ASCII encoding is 8 bits (1 byte), 
though it can fit in 7 bits.

An ISO-8895-1 character in ISO-8859-1 encoding is 8 bits (1 byte).
A Unicode character in UTF-8 encoding is between 8 bits (1 byte) and 
32 bits (4 bytes).

A Unicode character in UTF-16 encoding is between 16 (2 bytes) and 32 
bits (4 bytes), though most of the common characters take 16 bits. 
This is the encoding used by Windows internally.
 
A Unicode character in UTF-32 encoding is always 32 bits (4 bytes).

An ASCII character in UTF-8 is 8 bits (1 byte), and in UTF-16 - 16 bits.
The additional (non-ASCII) characters in ISO-8895-1 (0xA0-0xFF) would
take 16 bits in UTF-8 and UTF-16.

  Always 1 bit per character

  Always 256 bits

  It depends what the character is and what encoding it is in (8 bits for extended ASCII)

  Always 12 bits

 2. In "Peter Piper picked a peck of pickled peppers" the total number of characters is ….

  33 (spaces are never included in calculations)

  22 (excluding spaces)

  23 (including spaces)

  44 (including spaces)

 3. In normal ASCII encoding a bit of text that had 44 characters (including spaces) would require:

  8 bits per character making a total of 352 bits

  4 bits per character making a total of 44 x 4

  10 bits per character making a a total of 44 x 10 = 440

  1 bit per character making a total of 44 bits

 4. To recap: each character in an ASCII file uses 7 bits but most files use extended ASCII which is ___________________.

  4 bits per character

  8 bits per character

  2 bits per character

  14 (double) bits per character

 5. To calculate the file size of an ASCII text file, count the number of characters, including spaces and that will be ______________.

  the number of MB in the file

  the number of bits in the file

  the number of KB in the file

  the number of bytes in the file

 6. Once you have found the number of bytes contained in a file, to find the number of bits you just need to:

  multiply the number of bytes by 8

  multiply the number of bytes by 256

  multiply the number of bytes by itself

  none of these options

 7. The ASCII file size in bits =

  number of characters x 8

  number of characters x 2

  number of characters

  number of characters x number of bits

 8. How many bits and bytes are in this sentence?

  30 bytes and 339 bits

  9 bytes and 78 bits

  45 bytes and 280 bits

  46 bytes and 290 bits

 9. How many colours can be represented in an image with 8 bits?

  256

  33

  None

  25

 10. The number of pixels in an image is worked out by: image width x image height (in pixels)

  TRUE

  FALSE

 11. How many bytes are there per character in a text file?

  0.5

  1.5

  8

  1

 12. Which is the smallest of these data capacities?

  2049 bytes

  3GB

  1KB

  0.5MB

 13. The sample frequency has no effect on the quality of a recording.

  True

  False

 14. Which formula can be used to estimate the file size of an image?

  Number of pixels wide * number of bytes per pixel * number of pixels * 1.1

  Number of pixels * number of bytes per pixel

  Number of pixels wide * number of pixels high * number of bytes per pixel * 1.1

  Number of pixels * 1.1

 15. Which formulae can be used to estimate the file size of a sound file?

  Samples per second * number of seconds * 1.1

  Bytes per sample * channels * height + number of minutes

  Samples per second * samples per second * channels * duration

  Samples per second * bytes per sample * duration

 16. Just two bytes are needed to store 32,769 different colours?

  True

  False

 17. A file's size can be influenced by a number of factors but ultimately the more information a file stores, the smaller it will be.

  False

  True

 18. A sound engineer is recording a 30 second mono sound clip of some crows cawing outside the studio. Her recording equipment samples at 10 kHz and she is using 8-bit sampling. How big will the sound file be in bytes?

   300,000 bytes

  3000 bytes

  200 bytes

  2,400,000 bytes

 19. A sound recording will last for 10 seconds. It will need four microphones (i.e. four channels of sound needed) and for a good quality of sound, 16-bit sampling will be used at 5000 Hz frequency. How big will the sound file be in bytes?

  5,000 x 16 x 10 = 100,000 bytes

  5,000 x 16 x 10 = 800,000 bytes

  5 x 10 = 50 x 16 = 1,560,000 bytes

  It cannot be calculated

 20. An old recording has a size of 2.2 MB. The label on the box says that it was recorded in mono (one channel), that it had a recording sampling frequency of 20 kHz and used 8-bit sampling. How long would this piece of music last?

  20,000 seconds

  4 seconds

  10,000 seconds

  110 seconds


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