10 men and 6 women are to be seated in a row so that no two women sit together. The number of ways they can…

10 men and 6 women are to be seated in a row so that no two women sit together. The number of ways they can be seated, is
  1. $11 ! 10 !$
  2. $\frac{11 !}{6 ! 5 !}$
  3. $\frac{10 ! 9 !}{5 !}$
  4. $\frac{11 ! 10 !}{5 !}$

Solution

W W W W W W W W W First, we arrange 10 men in a row at alternate position. So, number of ways formula $=10$ ! Now, 6 women can arrange in 11 positions So, number of ways for women $={ }^{11} P_6$ Required number of $ \begin{aligned} S & =10 ! \times{ }^{11} P_6 \\ & =\frac{10 ! 11 !}{5 !} \end{aligned} $

Asked in: AP EAMCET 2013

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