Question
There are 6 positions on a shelf. You have 3 identical
pens and 3 distinct books. In how many ways can these articles be arranged such that all pens do not appear together?Solution
Total arrangements = 6! / 3! = 120
All pens together: Pens block + 3 books = 4! = 24
Required = 120 - 24 = 96
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