अंकों (1,2,3,4,5,6,7,8) से बिना पुनरावृत्ति (5) अंकों की कितनी संख्याएं बनेंगी जिनमें (1) और (8) साथ-साथ आएं?
How many (5)-digit numbers can be formed from (1,2,3,4,5,6,7,8) without repetition in which (1) and (8) are adjacent?
Explanation opens after your attempt
B. (1800)
Concept
Treat (1) and (8) as a block and choose the other (3) digits from (6). The total is \(\binom{6}{3}\cdot4!\cdot2!=960\).
Why this answer is correct
The correct answer is B. (1800). Treat (1) and (8) as a block and choose the other (3) digits from (6). The total is \(\binom{6}{3}\cdot4!\cdot2!=960\).
Exam Tip
(1) और (8) को ब्लॉक मानें और बाकी (3) अंक (6) में से चुनें। कुल \(\binom{6}{3}\cdot4!\cdot2!=960\) है।
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