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17 - Practice Test

 1. Analogue to Digital converter: takes real-world analogue data and converts it to a binary representation that can be stored on a computer

  DAC

  ADC

  ADV

  None of the above

 2. Data about data is referred to as:

  knowledge

  nonsense

  information

  metadata

 3. What is a 106 in Hexadecimal?

  23

  6A

  123

  2A

 4. 8 bits = 2 bytes

  TRUE

  FALSE

 5. Sound waves are ________ which means they are continuously changing.

  mixed

  digital

  analogue

  high

 6. The number of bits used to store each sample. The more bits used the better the accuracy of the sound file

  None of the above

  sample rate

  sample interval

  sample resolution

 7. The largest value you can have with four bits is:

  1010

  1111

  1101

  1000

 8. What is the result in binary after doing the left shift?
Binary Shift Example
=====================
The below number is no. 32 in Decimal. We want to multiply by 2.

Shift every bit to the left by one and insert a zero to the 
rightmost bit. The original leftmost bit is discarded.

128   64     32     16    8     4     2    1
=============================================
0     0      1     0     0    0    0    0

What is the Result in Binary?
======

128   64     32     16    8     4     2    1
=============================================
?     ?       ?      ?    ?     ?     ?    ?

  10000000

  11110001

  1000000

  11100101

 9. If we wish to ______ we shift every bit to the left by one and insert a zero to the rightmost bit. The original leftmost bit is discarded.

  add

  subtract

  divide

  multiply

 10. In decimal, you have the number 468, which is 111010100 in Binary. Shift it to the left to multiply by two and what happens?
Binary Shift Example
=====================
The below number is 468 in Decimal. We want to multiply by 2.

Shift every bit to the left by one and insert a zero to the 
rightmost bit. The original leftmost bit is discarded.

256   128   64     32     16    8     4     2    1
==================================================
1     1      1       0    1     0     1    0    0

What is the Result in Binary?
=============================
256   128   64     32     16    8     4     2    1
==================================================
???????????????????????????????????????????????????

  Nothing spectacular. It will work as expected

  You would get a result of 110101000 which is 424 - an overflow error has occurred

  It will add instead of multiply the numbers

  none of the above

 11. In the following example, can you spot the error. We are trying to divide 8 using binary shift.
The video will help, but you do not need it to answer the question.                                    Binary Shift Example
=====================
The below number is 8 in Decimal. We want to divide by 2.

Shift every bit to the right by one.
The original rightmost bit is discarded.

256   128   64     32     16    8     4     2    1
==================================================
0     0      0     0      0     1     0    0    0

What is the Result in Binary?
=============================
256   128   64     32     16    8     4     2    1
==================================================
 0     0     0      0      1    0     0     0    0 

  none of the above

  a single right shift has been applied but the result has not been added to another bit of '1'

  a single left shift has been applied instead of a single right shift

  two right shifts were necessary in order for the division to take place

 12. Can you spot the error in this binary shift (division)?
Binary Shift Example
=====================
The below number is 16 in Decimal. We want to divide by 4.

4 is 2 to the power of 2 (so we shift of two times to the right)

Shift every bit to the right by two. The original rightmost bit is discarded.

256   128   64     32     16    8     4     2    1
==================================================
0     0      0     0      1     0     0    0    0

What is the Result in Binary?
=============================
256   128   64     32     16    8     4     2    1
==================================================
 0     0     0      0      0    0     1     0    0 

= 4 in Decimal. 

  The shift should have been one to the right, and the right most bit should not have been discarded but added to 1

  There is no error. The calculation and shift has been performed correctly

  The shift should have been one twice to the left, not right.

  The shift should have been just once to the right

 13. What statement is true about this lossy compression of images?
datarep_compression_q1.jpg

  They are vastly different and hugely matter

  It is slightly more blurry but not enough to matter in most circumstances

  Compression has reduced the quality by a significant degree and should not be used

  None of the above

 14. What is the benefit of compressing an image file for a use on a website?

  All of the above

  It may offer the user speed in loading the page for a very slighy quality reduction

  It takes up less storage space on your website

  it would render five times faster

 15. A film could take up to an hour to download in uncompressed format whilst a compressed file could take just 12 minutes

  FALSE

  TRUE

 16. Lossless compression is when…

  reducing a file's size with NO loss of quality

  reducing file size with a massive reduction in quality

  reduing a file's size in exactly the same was as lossy compression

  reducing file size with an increase in quality

 17. Fill in the blanks for RLE
RLE
===================================================
One of the simplest examples of compression is RLE. 
RLE is a basic form of data compression that converts 
consecutive identical values into a code consisting of
 the character and the number __________________________________.
The more similar values there are, the more values can be compressed. 
The sequence of data is stored as a single value and count.

  marking the number of times the file has been compressed

  marking the number of bits contained in the file

  marking the length of the run.

  marking the binary file size

 18. In the following picture we compress …
datarep_compression_q3.jpg

  consecutive pixels by only replacing each run with one pixel from it and a counter showing how many items it contains.

  nothing at all

  random pixels by replacing each run with several pixels from it

  random pixels by replacing each run by four pixels from it.

 19. Run-length encoding isn’t a very effective option when compressing texts, but for images …
datarep_compression_q4.jpg

  None of the above

  where there are pixels it is even less useful

  where short runs of text bits happen to occur in sequence, it is useful

  where long runs of the identical pixels happen to occur it is quite useful.

 20. In "Peter Piper picked a peck of pickled peppers" the total no. of characters is ….

  33 (spaces are never included in calculations)

  22 (excluding spaces)

  44 (including spaces)

  23 (including spaces)

 21. A group of four bits, or half a byte, is sometimes called a ____________________

  byte or bit

  terrabyte or gigabyte

  kilobyte or megabyte

  nibble or nybble.

 22. 1 byte refers to …

  2 bits

  5 bits

  8 bits

  1 bit

 23. 1 byte can be used to store

  a number from 0 to 255

  114 minutes of DVD Video

  one mp3 song

   page of text from a novel

 24. This shows a memory stick with….
datarep_unitsofinformation_q1.jpg

  No memory

  16 GB of memory

  32 bits of memory

  16 bytes of memory

 25. bits, bytes, megabytes, gigabytes, terabytes etc are all used to…

  hold the parts of a computer together

  describe disk space, data storage or the capacity of system memory

  perform calculations and store memory

  create the mother board

 26. A bit can be used to:

  store a single number up to the value of 55

  store a single letter like A

  hold the answer to a yes/no or true/false question

  store a single number up to the value of 255

 27. A byte can be used to

  store a number from 0 to 512 billion

  store the word 'CAT'

  store a single letter like A

  store an audio sequence with just 10 notes

 28. The symbol for byte is uppercase B. 16 bytes would be written as

  16Bi

  16B

  16MB

  16BYTES

 29. A kilobyte is thought of as approximately 1000 bytes but to be accurate it is:

  1024 bytes (2 to the power of 10)

  102 bytes

  12 bytes

  2024 bytes (which is 2 to the power of 10)

 30. Have a look at the table below which shows the units of information leading to memory. Fill in the blanks
datarep_unitsofinformation_q2.jpg

  None of the above

  1000 Bytes

  1024 GB

  1024 TB