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Q23E
Expert-verifiedHow many ways are there for eight men and five women to stand in a line so that no two women stand next to each other? (Hint: First position the men and then consider possible positions for the women.)
The total number of possible arrangements is \(609,638,400\).
Number of men \( = 8\) and number of women \( = 5\).
The word "permutation" refers to the act or process of changing the linear order of an ordered set.
Formula:
\(_n{P_r} = \frac{{n!}}{{(n - r)!}}\)
First, consider the position of men.
Find the possible ways to arrange men in a row.
\(\begin{array}{l}P(8,8) = \frac{{8!}}{{(8 - 8)!}}\\P(8,8) = \frac{{8!}}{{0!}}\\P(8,8) = 40,320\end{array}\)
It is given that no two women stand next to each other.
The situation becomes:
\(O\;M\;O\;M\;O{\rm{ }}M\;O\;M\;O\;M\;O{\rm{ }}M\;O\;M\;O\;M\;O\)
There are \(9\) places for women. We can arrange \(5\) women in these 9 places.
Now, find the ways to place women:
\(\begin{array}{l}P(9,5) = \frac{{9!}}{{(9 - 5)!}}\\P(9,5) = \frac{{9!}}{{4!}}\\P(9,5) = 15,120\end{array}\)
Find the total number of possible arrangements:
Number of possible arrangements \(\; = 15,120 \times 40,320\)
Number of possible arrangements \( = 609,638,400\)
Hence, the total number of possible arrangements is \(609,638,400\).
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