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A-LevelMathematicsDifferential equationsMay/June 2020Paper 3 Q1012 Marks

A tank containing water is in the form of a hemisphere. The axis is vertical, the lowest point is A and the radius is r, as shown in the diagram. The depth of water at time t is h. At time t = 0 the tank is full and the depth of the water is r. At this instant a tap at A is opened and water begins to flow out at a rate proportional to √h. The tank becomes empty at time t = 14. The volume of water in the tank is V when the depth is h. It is given that V = ⅓π(3rh² – h³).

📋 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 12 marks.

Source

This question appeared in the Cambridge A-Level Mathematics May/June 2020 examination, Paper 3 Variant 3.

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