There are thirty volumes of a magazine on the book shelf. The number of ways in which, they can be arranged, so that two particular volumes are kept side by side and another two volumes are not side b

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There are thirty volumes of a magazine on the book shelf. The number of ways in which, they can be arranged, so that two particular volumes are kept side by side and another two volumes are not side by side, is

TestHub · Accepted Answer

Let us consider the case in which the first two particular volumes out of 30 are always together and the other two particular volumes are anywhere. $∴ Required Ways = (29)! 2!$

\item[] Now, let us remove all those cases from above in which the other two particular books are always together, we are automatically left with the arrangement in which the first two volumes are always together and the other two volumes are never together.

Mathematics - Permutation & Combination Question with Solution | TestHub

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