Unit 2: Data Representation

Question 1

Which numbers are stored in one bit?

Answer 1

0 and 1

Question 2

How many bits are there in a nibble and a byte?

Answer 2

Nibble = 4 bits
Byte = 8 bits

Question 3

What are the units after a kilobyte?

Answer 3

Megabyte, Gigabyte, Terabyte, Petabyte

Question 4

What is zero as an 8 bit Binary number

Answer 4

0000 0000

Question 5

What is 255 in Binary?

Answer 5

1111 1111

Question 6

What is 39 as an 8 bit Binary number?

Answer 6

0010 0111

Question 7

Convert C in hexadecimal to denary

Answer 7

12

Question 8

What’s 2B hexadecimal in Binary?

Answer 8

2B = 162 + 1B = 32 + 11 = 43
0010 1011

Question 9

What’s 1010 0011 in hexadecimal?

Answer 9

A3

Question 10

Calculate
1001 0101
+ 0010 0110

Answer 10

1001 0101
+ 0010 0110
________________
1011 1011

Question 11

Explain what effect a left and right shift have

Answer 11

Left shift doubles the number
The right shift halves the number

Question 12

Calculate the left shift of 0110 1011

Answer 12

1101 0110

Question 13

How many bits are in the extended ASCII?

Answer 13

8 bits

Question 14

How many characters does ASCII allow for?

Answer 14

256

Question 15

How many bytes are in Unicode?

Answer 15

16-bit has 2 bytes
32-bits has 4 bytes

Question 16

If ‘f’ has the ASCII code 102, what is the ASCII code for ‘g’?

Answer 16

103

Question 17

How many bytes are needed to store “Hello everyone.”?

Answer 17

15 (remember to include space and the full stop)

Question 18

A bitmap graphic is made up of…

Answer 18

Individual pixels

Question 19

Each … is represented in Binary

Answer 19

Pixel

Question 20

The … determines the number of available colours for an image

Answer 20

Number of bits per pixel

Question 21

Image … holds data about the image, such as …

Answer 21

Metadata
Colour depth, resolution, date created, author

Question 22

The greater the … of the image, the greater the file size

Answer 22

Resolution

Question 23

The sample rate is measured in what unit?

Answer 23

Hertz (Hz)

Question 24

The number of bits available to store each sample is known as what?

Answer 24

Bit depth

Question 25

What is the formula for calculating the size of an uncompressed music file?

Answer 25

Sample rate x bit depth x duration

Question 26

Track1.wav uses a sample rate of 20 kHz, Track2.wav uses a sample rate of 10 kHz. Which file is the higher quality? Which is the larger file size?

Answer 26

Track1 is higher quality and a larger file size

Question 27

Explain the need for compression

Answer 27

Compression reduces the size of files, which makes them smaller to store and transmit – this enables services such as streaming music and video

Question 28

Explain Lossy compression

Answer 28

The compression technique will lose some of the original information

Question 29

Explain some of the effects of 
 lossy compression on 
 images and sound files

Answer 29

Noise at edges and blocks are digital artefacts from 
 lossy compression

Question 30

Explain Lossless compression

Answer 30

No data is lost by using a lossless compression algorithm