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The total number of ways in which 4 boys...

The total number of ways in which 4 boys and 4 girls can form a line, with boys and girls alternating, is

A

(4!)2

B

8!

C

2(4!)^2

D

`4!.""^(5)P_(4)`

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The correct Answer is:
To solve the problem of arranging 4 boys and 4 girls in a line such that they alternate, we can break it down into a few steps. ### Step-by-Step Solution: 1. **Identify the Arrangements**: There are two possible arrangements for alternating boys and girls: - Case 1: Boy-Girl-Boy-Girl-Boy-Girl-Boy-Girl - Case 2: Girl-Boy-Girl-Boy-Girl-Boy-Girl-Boy 2. **Calculate Arrangements for Case 1**: - In Case 1, we have 4 boys and 4 girls. - The boys can be arranged in their positions in \(4!\) (factorial of 4) ways. - The girls can also be arranged in their positions in \(4!\) ways. - Therefore, the total arrangements for Case 1 = \(4! \times 4!\). 3. **Calculate Arrangements for Case 2**: - Similarly, in Case 2, the arrangement is the same as Case 1. - The boys can again be arranged in \(4!\) ways and the girls in \(4!\) ways. - Therefore, the total arrangements for Case 2 = \(4! \times 4!\). 4. **Combine the Cases**: - Since both cases are mutually exclusive, we add the total arrangements from both cases. - Total arrangements = Arrangements from Case 1 + Arrangements from Case 2 = \(4! \times 4! + 4! \times 4!\). - This simplifies to \(2 \times (4! \times 4!)\). 5. **Calculate \(4!\)**: - \(4! = 4 \times 3 \times 2 \times 1 = 24\). 6. **Final Calculation**: - Now, substituting \(4!\) into the total arrangements: - Total arrangements = \(2 \times (24 \times 24) = 2 \times 576 = 1152\). ### Conclusion: The total number of ways in which 4 boys and 4 girls can form a line, with boys and girls alternating, is **1152**.
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OBJECTIVE RD SHARMA ENGLISH-PERMUTATIONS AND COMBINATIONS-Exercise
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