# 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

None of the above

2. Data about data is referred to as:

knowledge

nonsense

information

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.

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

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

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 whenâ€¦

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 â€¦

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 isnâ€™t a very effective option when compressing texts, but for images â€¦

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 â€¦.

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 â€¦

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 withâ€¦.

No memory

16 GB of memory

32 bits of memory

16 bytes of memory

25. bits, bytes, megabytes, gigabytes, terabytes etc are all used toâ€¦

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

None of the above

1000 Bytes

1024 GB

1024 TB