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S4 ICT: Data Representation and File Size (Paper 2 (intermediate))
Tutor Prep Guide · Bits and bytes, the 1024 based KB, MB and GB scale, binary and hexadecimal conversion, ASCII characters, image resolution and colour depth, sound sampling rate and bit depth, video and compression, plus the usual mistakes in file size calculation
S4 ICT: Data Representation and File Size (Paper 2 (intermediate))
Paper 2 (intermediate): ten questions on data representation and file size, with answers and notes.
Direct answers Level: S4 ICT; format: byte conversion, binary and hexadecimal, image and sound file size, compression and unit errors.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: S4 ICT: Data Representation and File Size |
| Level | S4 |
02 Questions (10 items)
- FoundationA 16 GB USB drive stores 4 MB photos. How many photos fit?
- FoundationHow many MB are there in 2 GB?
- FoundationWhat is the binary number 11001100 in denary?
- IntermediateWhat is the hexadecimal number 2F in denary?
- IntermediateWhat is the denary number 200 in hexadecimal?
- IntermediateAn uncompressed 1024 by 768 image uses 24-bit colour. How many bytes does it take?
- ChallengeA mono recording is sampled at 8000 Hz with 16-bit depth for 10 seconds. How large is the file?
- ChallengeHow many bytes are there in 4 MB?
- ChallengeA phone has 64 GB of storage and three quarters is used. How much is left?
- Error redoError clinic: a student calculated 11 520 000 bytes for an 800 by 600 image at 24-bit colour. What is correct?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 4096 photos | 16 GB is 16 384 MB, and dividing by 4 MB gives 4096 photos. |
| 2 | 2048 MB | One GB is 1024 MB, so 2 times 1024 gives 2048 MB. |
| 3 | 204 | Adding the place values 128, 64, 8 and 4 gives 204. |
| 4 | 47 | The digit 2 stands for 32 and F stands for 15, giving 47 in total. |
| 5 | C8 | 200 divided by 16 gives quotient 12 and remainder 8, and 12 is written as C, so the answer is C8. |
| 6 | 2 359 296 bytes (about 2.25 MB) | 1024 times 768 gives 786 432 pixels, and multiplying by 3 bytes gives 2 359 296 bytes. |
| 7 | 160 000 bytes | Each second holds 8000 samples of 2 bytes, which is 16 000 bytes, so ten seconds give 160 000 bytes. |
| 8 | 4 194 304 bytes | Four times 1024 times 1024 gives 4 194 304 bytes. |
| 9 | 16 GB | The used part is 48 GB, so 64 minus 48 leaves 16 GB. |
| 10 | 1 440 000 bytes | The figure 11 520 000 is the number of bits, so it must be divided by 8 to give 1 440 000 bytes. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Write down the conversion factors first (1 byte = 8 bits, 1 KB = 1024 bytes), then multiply the number of pixels or samples by the bits per unit, and only at the end divide by 8.Tutor Registration →
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