Ria has 4 green marbles and 8 red marbles. She arranges them in a circle randomly. If the probability that no two green marbles are adjacent is p q where the positive integers p, q have no common factors other than 1 , what is p+q ?

Question

Quantrex Academy · Accepted Answer

Correct answer: 40

Favourable ways =7!^8 C ₄ 4 ! Sample space =11 ! aligned & Pr = 7!8! 4!4! 4! 11! = 7 6 5 4! 4! 11 10 9 = 7 33 & p+q=40 aligned

Ria has 4 green marbles and 8 red marbles. She arranges them in a circle randomly. If the probability that no two green marbles are adjacent is p q where the positive integers p, q have no common factors other than 1 , what is p+q ?

Correct answer

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