(8) रसायन और (5) जीवविज्ञान पुस्तकों में से (4) पुस्तकें चुननी हैं जिनमें कम से कम (2) रसायन पुस्तकें हों। कितने तरीके हैं?
From (8) chemistry and (5) biology books (4) books are to be selected with at least (2) chemistry books. How many ways are there?
Explanation opens after your attempt
Correct Answer
C. (560)
Concept
The cases are (2), (3), and (4) chemistry books. The correct sum is \(\binom{8}{2}\binom{5}{2}+\binom{8}{3}\binom{5}{1}+\binom{8}{4}=630\).
Why this answer is correct
The correct answer is C. (560). The cases are (2), (3), and (4) chemistry books. The correct sum is \(\binom{8}{2}\binom{5}{2}+\binom{8}{3}\binom{5}{1}+\binom{8}{4}=630\).
Exam Tip
मामले (2), (3) और (4) रसायन पुस्तकों के हैं। कुल \(\binom{8}{2}\binom{5}{2}+\binom{8}{3}\binom{5}{1}+\binom{8}{4}=630\) नहीं बल्कि सही जोड़ (280+280+70=630) है।
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