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A-Level Probability: worked solution
2 marks. Full working, one step per line.
Question
Kitty owns 5 small, 3 medium and 2 large spherical charms, all uniquely designed. She sets all 10 in a circle on a corkboard with equal-sized charms adjacent. In how many ways?
Worked answer
Equal-sized charms must be adjacent, so the 5 small, 3 medium and 2 large form 3 blocks arranged in a circle. Circular arrangements of 3 distinct blocks = (3-1)! = 2. Internal orderings: 5! (small) x 3! (medium) x 2! (large) = 120 x 6 x 2 = 1440. Total = 2 x 1440 = 2880.
Practise this topic
This question is part of A-Level Probability, in A-Level H2 Maths.
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