(5) सफेद और (7) काली गेंदों में से कुल (4) गेंदें चुननी हैं जिनमें सभी काली हों। कितने तरीके हैं?
From (5) white and (7) black balls, (4) balls are to be selected and all must be black. How many ways are there?
Explanation opens after your attempt
B. (35)
Concept
All balls must be black, so there are \(\binom{7}{4}=35\) ways. The white balls are not used.
Why this answer is correct
The correct answer is B. (35). All balls must be black, so there are \(\binom{7}{4}=35\) ways. The white balls are not used.
Exam Tip
सभी काली गेंदें चाहिए इसलिए \(\binom{7}{4}=35\) तरीके हैं। बाकी सफेद गेंदों का प्रयोग नहीं होगा।
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