अक्षरों (A,B,C,D,E,F) से बने शब्दों में (B) हमेशा (A) के बाद आए, ऐसी कितनी व्यवस्थाएं हैं?
Among arrangements of letters (A,B,C,D,E,F), how many have (B) always appearing after (A)?
Explanation opens after your attempt
Correct Answer
C. (360)
Concept
In the total (6!) arrangements, the two orders of (A) and (B) are equally likely, so half are valid. Symmetry saves time in order-condition questions.
Why this answer is correct
The correct answer is C. (360). In the total (6!) arrangements, the two orders of (A) and (B) are equally likely, so half are valid. Symmetry saves time in order-condition questions.
Exam Tip
कुल (6!) व्यवस्थाओं में (A) और (B) के दोनों क्रम बराबर हैं, इसलिए आधी व्यवस्थाएं सही हैं। क्रम-शर्त में सममिति से समय बचता है।
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