(12) अलग-अलग अक्षरों में से (5) अक्षर चुनने हैं जिनमें (a) और (b) में से ठीक एक हो तथा (c) और (d) दोनों न हों। कितने तरीके हैं?
From (12) distinct letters (5) letters are to be selected with exactly one of (a,b) and not both (c,d). How many ways are there?
Explanation opens after your attempt
C. (300)
Concept
Choose (1) from (a,b), then choose the remaining (4) so that (c,d) are not both included. The correct expression is (\binom{2}{1}\left\(\binom{10}{4}-\binom{8}{2}\right\)=364).
Why this answer is correct
The correct answer is C. (300). Choose (1) from (a,b), then choose the remaining (4) so that (c,d) are not both included. The correct expression is (\binom{2}{1}\left\(\binom{10}{4}-\binom{8}{2}\right\)=364).
Exam Tip
(a,b) में से (1) चुनकर बाकी (4) ऐसे चुनें कि (c,d) दोनों साथ न आएं। तरीके (\binom{2}{1}\left\(\binom{10}{4}-\binom{8}{2}\right\)=364) नहीं, सही (\binom{2}{1}\left\(\binom{10}{4}-\binom{8}{2}\right\)=364) है।
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