Data representation

Revision tip: Focus on the things you find difficult first.

Task Time (minutes) a

1. Complete self assessment sheet. 22. Read through the chapter on data representation. 153. Work through the questions on the revisiontemplate focusing on weaker areas first.

25

4. Attempt the multiple choice test on Edmodo. 105. Attempt the past paper exam questions. 206. Mark past paper exam paper questions. 157. Read through the chapter on data representation. 158. Attempt the multiple choice test on Edmodo again. 10

“Every lesson counts – don’t waste a minute.”

Binary numbers (base 2)1. Convert 10110 to denary (base 10)

(1 mark)

2. Convert 1001001 to denary (base 10)(1

mark)

3. Convert 11001101 to denary (base 10)(1

mark)

4. Convert 11111001 to denary (base 10)(1

mark)

Exam tip: When converting binary numbers in the exam, draw atable to show your workings.

4. How many gigabytes are there in 3 terabytes?(1

mark)……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................5. How many kilobytes are there in 2.5 megabytes?

(1 mark)

……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................

Denary (base 10) to binary (base 2)26 (base 10) as a binary number (base 2)

1. Convert 34 (base 10) to binary (base 2). Show your workings.(1

mark)

2. Convert 115 (base 10) to binary (base 2). Show your workings.(1

mark)

3. Convert 99 (base 10) to binary (base 2). Show your workings.(1

mark)

4. Convert 76 (base 10) to binary (base 2). Show your workings.(1

mark)

Adding binary numbers

1. Add 101100 and 111001 in binary.(2

marks)

2. Add 101111 and 10011 in binary.(2

marks)

3. Add 1001101 and 101011 in binary.(2

marks)

4. Add 11011001 and 10010111 in binary.(2

marks)

Hexadecimal numbers

1. Convert the hexadecimal number 3A to denary.(2 marks)

2. Convert the hexadecimal number AD to denary.(2 marks)

3. Convert the hexadecimal number 5E to denary.(2 marks)

4. Convert the denary number 91 to hexadecimal.(2 marks)

5. Convert the denary number 169 to hexadecimal.(2 marks)

6. Convert the denary number 51 to hexadecimal.(2 marks)

Binary to Hex & back again1. Convert 10110110 to hexadecimal.

(2 marks)

2. Convert 11001001 to hexadecimal.(2 marks)

3. Convert 10011011 to hexadecimal.(2 marks)

4. Convert A5 to binary.(2 marks)

5. Convert 7D to binary.(2 marks)

6. Convert F3 to binary.(2 marks)

Characters1. What happens if you sort the list ‘Gorilla’, ‘bear’, ‘Elephant’, ‘Cat’, ‘dog’ in

a computer program using ASCII or Unicode to represent the character set.

(2 marks)……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................

Images1. How many colours can be represented in a 4 bit

colour system?

(1 mark)……………………………………………………............................................................................................................……………………………………………………..................

2. The image opposite shows the metadata of an image. What is… (3 marks)

a) the size of the image: ………………………

b) the colour depth: ……………………………

c) the resolution: ………………………………

2. What is the difference between using the ASCII character set and the Unicode character set?

(2 marks)……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................……………………………………………………................................................................................................................................................................

3. What are the main factors affecting the size of the file needed to store an image?

(3 marks)……………………………………………………............................................................................................................……………………………………………………..................……………………………………………………............................................................................................................……………………………………………………..................……………………………………………………............................................................................................................……………………………………………………..................……………………………………………………............................................................................................................……………………………………………………..................

Sound1. How does sample rate affect the quality of the playback for an MP3

sound track?(2 marks)

…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................

Instructions1. How does the computer tell the difference between instructions and

data?(2 marks)

……………………………………………………................................................. ……………………………………………………................................................. ……………………………………………………................................................. ……………………………………………………................................................. …………………………………………………….................................................

2. What factors affect the file size for a sampled MP3 soundtrack?(4 marks)

…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................…………………………………………………….................................................

2. How are instructions stored in binary in a computer?(2 marks)

……………………………………………………................................................. ……………………………………………………................................................. ……………………………………………………................................................. ……………………………………………………................................................. …………………………………………………….................................................

Exam tip: Don’t confuse sample rate and bit rate; they are different. The sample rate ishow frequently the data is sampled; the bit rate is the amount of data stored at each point.

Past paper exam questions.2011 past paper.

Past paper answers.2011 past paper.

Notes: What do I need to improve?

Past paper exam questions.2011 past paper.

Exam tip: When converting numbers in exam questions make sureyou show your workings.

Past paper answers.2011 past paper.

Notes: What do I need to improve?

Past paper exam questions.2012 past paper.

Past paper answers.2012 past paper.

Notes: What do I need to improve?

Past paper exam questions.2013 past paper.

Past paper answers.2013 past paper.

Notes: What do I need to improve?