(6) पत्रों को (6) सही लिफाफों में डालते समय ठीक (2) पत्र गलत लिफाफों में जाएं, ऐसे कितने तरीके हैं?
When (6) letters are put into (6) addressed envelopes, how many ways have exactly (2) letters in wrong envelopes?
Explanation opens after your attempt
C. (15)
Concept
Choose the (2) wrong letters in \(^{6}C_2\) ways, and they must swap with each other. For exactly (2) wrong, those two letters interchange.
Why this answer is correct
The correct answer is C. (15). Choose the (2) wrong letters in \(^{6}C_2\) ways, and they must swap with each other. For exactly (2) wrong, those two letters interchange.
Exam Tip
गलत जाने वाले (2) पत्र \(^{6}C_2\) तरीकों से चुनें और वे आपस में बदलेंगे। ठीक (2) गलत होने पर वही दो पत्र अदला-बदली करते हैं।
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