(9) सदस्यों में से (4) चुनने हैं। एक जोड़ी (P) के दोनों सदस्य साथ नहीं चुने जा सकते और दूसरी जोड़ी (Q) से कम से कम (1) सदस्य चुना जाना चाहिए। दोनों जोड़ियां अलग हैं। कितने चयन संभव हैं?
From (9) members, (4) are to be chosen. Both members of pair (P) cannot be chosen together and at least (1) member of pair (Q) must be chosen. The two pairs are disjoint. How many selections are possible?
Explanation opens after your attempt
A. (80)
Concept
First count selections with at least (1) member from (Q): \(^{9}C_{4}-^{7}C_{4}=91\). Subtract \(^{7}C_{2}-^{5}C_{2}=11\) cases containing both members of (P), giving (80).
Why this answer is correct
The correct answer is A. (80). First count selections with at least (1) member from (Q): \(^{9}C_{4}-^{7}C_{4}=91\). Subtract \(^{7}C_{2}-^{5}C_{2}=11\) cases containing both members of (P), giving (80).
Exam Tip
पहले (Q) से कम से कम (1) सदस्य वाले चयन \(^{9}C_{4}-^{7}C_{4}=91\) हैं। इनमें (P) की दोनों सदस्य वाली \(^{7}C_{2}-^{5}C_{2}=11\) स्थितियां घटाएं, उत्तर (80)।
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