O-LevelAdditional MathematicsPermutations and combinationsMay/June 2021Paper 1 Q69 Marks
(a) (i) Find how many different 5-digit numbers can be formed using the digits 1, 3, 5, 6, 8 and 9. No digit may be used more than once in any 5-digit number. (ii) How many of these 5-digit numbers are odd? (iii) How many of these 5-digit numbers are odd and greater than 60000? (b) Given that 45×"C4 = (n + 1)x"+1C5, find the value of n.
📋 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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