(9) छात्रों में से (2) छात्रों को प्रथम और द्वितीय स्थान देने के तरीके कितने हैं?
In how many ways can first and second positions be given to (2) students from (9) students?
Explanation opens after your attempt
B. (72)
Concept
The positions are ordered, so \({}^{9}P_{2}=9\times8=72\). Use permutation in ranking questions.
Why this answer is correct
The correct answer is B. (72). The positions are ordered, so \({}^{9}P_{2}=9\times8=72\). Use permutation in ranking questions.
Exam Tip
स्थान क्रम वाले हैं इसलिए \({}^{9}P_{2}=9\times8=72\)। रैंकिंग में क्रमचय का प्रयोग करें।
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