estions","basePath":"/gcse/computer-science/aqa/data-compression/questions","formulaUrl":null,"initialIndex":5,"initialQuestionWindow":[{"id":"0ab264e5-e293-4736-91b6-fd500dfb6b02","revisionId":"d7ff49a3-ba3b-4036-ae1d-4bad0be7c4a6","questionNumber":null,"questionType":"LA","specification":"","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"1707c53f-edf3-4060-8648-6828dbf3e8cd","label":null,"content":"An automated deep-bore mining probe transmits mineral type readings as it drills downwards. Explain how Run-Length Encoding (RLE) can be used to compress this geological data stream. In your explanation, you must include a short, concrete example of a raw sequence from this probe and its resulting compressed form under RLE.","markscheme":"- Explains that RLE identifies runs of consecutive identical mineral readings and encodes each run as a single instance of the mineral code paired with a count of its consecutive occurrences. M1\n- Provides a valid, clear geological example showing the sequence before and after RLE compression (e.g., 'GGGGGGSS' representing 6 Granite and 2 Shale compressing to '6G 2S' or '6, G, 2, S'). A1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"1cb71686-bddf-4766-bac7-646e97cdb718","revisionId":"535ded4d-9fa0-4d62-953d-e0ce4b65b583","questionNumber":null,"questionType":"LA","specification":"","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"94f84fa6-2ec7-4dd9-b13e-4190a6f0f560","label":null,"content":"A Huffman tree has been created for the phrase 'RED ROVER'.\n\n![Huffman tree diagram for RED ROVER](https://assets.mathsgenie.co.uk/aqa-qb/5ed15dd3-5624-4425-9ee0-871d280fcadf.png)\n\nWhat is the correct binary encoding for the substring **ROVE**?\n\n| Letter | Binary Encoding |\n| :--- | :--- |\n| R | |\n| O | |\n| V | |\n| E | |\n\nWrite your final full sequence below your table.","markscheme":"- Correctly identifies at least three of the individual character encodings: $R = 11$, $O = 100$, $V = 101$, $E = 00$ M1\n- Correctly assembles the final binary sequence for the substring **ROVE** as $1110010100$ A1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"2517e7f4-de71-4ffb-ad43-2cd8a3eaa98f","revisionId":"cdcdd0d8-cc96-4a46-a1c2-ee09b6656097","questionNumber":null,"questionType":"LA","specification":"","difficulty":3,"difficultyBand":"easy","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"c75b1f8e-0a01-4164-8397-428fb698fc34","label":null,"content":"When a Huffman tree is used, the string in **Figure 1** can be represented using 98 bits.\n\n### Figure 1\n`CYBER SECURITY PROTOCOLS`\n\nThe 24-character string shown in **Figure 1** could also be encoded using standard 8-bit ASCII.\n\nHow many bits are **saved** when Huffman coding is used rather than ASCII to represent the string shown in **Figure 1**?\n\nYou **must** show your working.","markscheme":"- Calculates the ASCII representation size: $24 \\times 8 = 192$ bits M1\n- Subtracts the Huffman bits to find the number of bits saved: $192 - 98 = 94$ bits (or follows through from an incorrect ASCII product) A1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"gcse_computer_science__aqa","summaries":[{"id":"01aceeda-575c-4ced-bc96-ba092de79c7e","difficultyBand":"medium","calculatorUse":null},{"id":"03fe5cea-6efd-45d9-aa60-75964ab4705a","difficultyBand":"easy","calculatorUse":null},{"id":"07d36a1a-5c14-476d-80ea-f2079e422bfb","difficultyBand":"easy","calculatorUse":null},{"id":"0ab264e5-e293-4736-91b6-fd500dfb6b02","difficultyBand":"easy","calculatorUse":null},{"id":"0fc37e4c-7cae-4c1a-9fb3-66f966107332","difficultyBand":"medium","

Data compression

Question 4

Data compression Questions

Data compression

Question 4

Data compression Questions