(7) अलग-अलग अक्षरों से (4) अक्षरों के गुप्त-कोड कितने बनेंगे यदि पुनरावृत्ति नहीं है?
How many (4)-letter codes can be formed from (7) distinct letters if repetition is not allowed?
Explanation opens after your attempt
A. (840)
Concept
Order matters in a code, so \(^{7}P_4=840\). In exams, think of permutation when forming codes.
Why this answer is correct
The correct answer is A. (840). Order matters in a code, so \(^{7}P_4=840\). In exams, think of permutation when forming codes.
Exam Tip
गुप्त-कोड में क्रम महत्वपूर्ण है, इसलिए \(^{7}P_4=840\)। परीक्षा में code बनने पर permutation सोचें।
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