SOLUTION: Five math books and three science books are to be arranged at random in
a bookshelf. What is the probability that books of the same subject are placed
together?
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-> SOLUTION: Five math books and three science books are to be arranged at random in
a bookshelf. What is the probability that books of the same subject are placed
together?
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Question 1153769: Five math books and three science books are to be arranged at random in
a bookshelf. What is the probability that books of the same subject are placed
together? Answer by ikleyn(52808) (Show Source):
The number of favorable permutations is
5!*3! + 3!*5! = 120*6 + 6*120 = 720 + 720 = 1440 = 2*6!
(MMMMMSSS + SSSMMMMM) <<<---=== it is the SCHEME of placing (!)
The number of all permutations is (5+3)! = 8!
Therefore, the probability under the question is
P = = = = = . ANSWER
