These questions and activities are designed to help you practise and revise key topics for your End-of-Unit (EOU) assessment on data representation, binary arithmetic, and multimedia compression.
The questions are based directly on your course materials and will help you check your understanding of how computers store images, sound, text, and numbers. You'll also practise important calculations, conversions, and process explanations that are likely to appear in the EOU.
Before beginning, add a new slide in your WBK called EOU REVISION and add your answers to these questions after that slide. Work through each section carefully and take time to explain your thinking where required—this is your chance to build confidence and fill any gaps before the test.
Answer each in one word or one full sentence.
What is a pixel?
What does ASCII stand for?
State one reason computers use binary.
What does a left binary shift do to a number?
What is metadata?
What is the maximum denary number you can represent using 8-bit binary?
Define “bit depth” in sound.
What is the purpose of file compression?
What unit is used to measure storage size just above megabytes?
What does Unicode allow that ASCII does not?
Show working clearly.
Convert the binary number 11001101 to denary.
Convert 201 into 8-bit binary.
Convert the hexadecimal value 3F into binary.
Convert 2.4 GB into megabytes.
Convert 4,500,000 bytes into megabytes (base-10).
Show all steps.
Calculate the uncompressed file size in KB for an image that is 300 × 400 pixels with 24-bit colour.
An audio file is mono, 22,050 Hz sample rate, 8-bit depth, and lasts 60 seconds. Calculate its size in bytes.
How many bits are required to store a 20-character text file using ASCII?
A video clip is stereo, 44,100 Hz, 16-bit, and lasts 45 seconds. What is the file size in MB?
A file is compressed from 6 MB to 2 MB. What percentage reduction is that?
Answer in 3–6 sentences.
Describe how a bitmap image is stored in binary. Include the role of pixels and colour depth.
Explain what happens when an 8-bit binary addition causes overflow.
Describe how sampling is used to store sound in binary.
Compare 8-bit and 24-bit colour in terms of file size and image quality.
Explain how binary shifts can help with fast mathematical operations in a computer.
Answer in full paragraphs (4–6 sentences).
A game developer needs to balance file size and image quality for an online game. Should they use lossy or lossless compression for character graphics? Justify your answer.
A company stores thousands of scanned contracts. Should they store these files using standard ASCII or Unicode? Why?
Discuss with your partner and agree on written answers together.
In your own words, write a simple explanation of how binary, file size, and compression are connected.
Imagine you’re explaining to a younger student why images and sounds have different methods of being stored in binary. Write 3–5 sentences explaining this clearly.
A pixel is the smallest unit of an image, storing a single colour.
ASCII stands for American Standard Code for Information Interchange.
Computers use binary because their hardware only has two states: on (1) and off (0).
A left binary shift doubles the number by shifting all bits one place to the left.
Metadata is extra information stored with an image, such as dimensions or file type.
The maximum denary number you can represent with 8-bit binary is 255.
Bit depth in sound means the number of bits used to store each sample.
The purpose of file compression is to reduce file size for storage and faster transfer.
The unit just above megabytes is gigabytes (GB).
Unicode allows representation of thousands of characters including emojis and scripts like Chinese, which ASCII does not.
11. 11001101 in denary = 205.
12. 201 in 8-bit binary = 11001001.
13. Hex 3F = Binary 00111111.
14. 2.4 GB = 2,400 MB.
15. 4,500,000 bytes = 4.5 MB (base-10).
16. 300 × 400 × 24 = 2,880,000 bits = 360,000 bytes = 360 KB.
17. 22,050 × 60 × 8 × 1 = 10,584,000 bits = 1,323,000 bytes.
18. 20 characters × 1 byte = 160 bits (20 bytes).
19. 44,100 × 45 × 16 × 2 = 63,504,000 bits = 7.94 MB.
20. (6 - 2) ÷ 6 × 100 = 66.7% reduction.
21. A bitmap image is stored in binary as a grid of pixels. Each pixel stores a binary value that represents its colour. The number of bits used per pixel depends on the colour depth. All pixel values are stored in sequence, allowing the image to be rebuilt accurately when opened. Higher resolution and more colour depth increase file size.
22. In an 8-bit system, the maximum value is 255. If an addition result goes above 255, it requires more than 8 bits. This extra bit is lost, causing the value to reset or wrap around to 0, which is known as overflow. It results in incorrect calculations and must be managed in software or hardware.
23. Sound is captured using sampling. The computer records the amplitude of a sound wave at regular intervals (sample rate). Each measurement is then stored as a binary number using a set bit depth. Higher sample rates and bit depth create better quality but larger files.
24. 8-bit colour allows 256 colours and creates smaller file sizes but lower quality. 24-bit allows over 16 million colours and provides more detail and realistic images. However, 24-bit images take up much more storage. The choice depends on the intended use and required image quality.
25. Binary shifts speed up calculations. A left shift multiplies the number by powers of 2, and a right shift divides it. These operations are faster for the computer than regular multiplication or division. Shifts are useful in graphics, game logic, and low-level hardware calculations.
26. The developer should use lossy compression for character graphics in an online game. Lossy formats reduce file size significantly, making downloads and gameplay faster. While some quality is lost, it's often not noticeable to players. This improves performance, especially on low-bandwidth networks. Lossy formats like JPEG are widely supported and balance quality with efficiency.
27. The company should use Unicode to store the scanned contracts. Although ASCII is smaller, Unicode supports more characters and languages. This ensures the contracts display correctly across systems and futureproofs the data. Unicode avoids misrepresentation of foreign symbols, legal characters, and formatting issues.
28. Binary is how computers store all types of data, including images and sound. File size is the amount of binary data needed to store something. Compression reduces file size by removing repeated or unnecessary binary data. These three ideas are linked because they all affect how efficiently data is stored and transferred.
29. Images are made of pixels, while sounds are waves. To store images, each pixel’s colour is saved as a binary code. For sound, the volume of the wave is measured at intervals and stored as binary samples. The structure of the data is different, so the storage method must match the type of media being saved.