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A-LevelMathematicsDifferential equationsOct/Nov 2021Paper 3 Q1011 Marks

A large plantation of area 20 km² is becoming infected with a plant disease. At time t years the area infected is x km² and the rate of increase of x is proportional to the ratio of the area infected to the area not yet infected. When t = 0, x = 1 and dx/dt = 1.

Q: What topic does this question test?

This question tests Differential equations in A-Level Mathematics (syllabus code 9709). It is worth 11 marks.

📋 Examiner Report & Trap Analysis

Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...

🎯 Mark Scheme Breakdown

Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.

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About This A-Level Mathematics Question

Topic

This structured question tests Differential equations in A-Level Mathematics (syllabus code 9709). It is worth 11 marks.

Source

This question appeared in the Cambridge A-Level Mathematics Oct/Nov 2021 examination, Paper 3 Variant 3.

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