Digits (1,2,3,4,5,6,7) से repetition allowed (4)-digit numbers में exactly (2) positions पर even digits हों, तो count कौन-सी है?
Using digits (1,2,3,4,5,6,7) with repetition allowed, if exactly (2) positions contain even digits in a (4)-digit number, what is the count?
Explanation opens after your attempt
Correct Answer
A. \(^{4}C_2\cdot3^2\cdot4^2\)
Concept
Choose the even positions, then each has (3) even choices and the rest have (4) odd choices. In exams choose positions first in exactly conditions.
Why this answer is correct
The correct answer is A. \(^{4}C_2\cdot3^2\cdot4^2\). Choose the even positions, then each has (3) even choices and the rest have (4) odd choices. In exams choose positions first in exactly conditions.
Exam Tip
Even positions चुनें, उन पर (3) even choices और बाकी पर (4) odd choices हैं। परीक्षा में exactly condition में positions first चुनें।
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