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JEE Mains · Maths · STD 11 - 6. permutation and combination
The number of ways in which an examiner can assign \(30\) marks to \(8\) questions, giving not less than \(2\) marks to any question, is
- A \(^{30}{C_7}\)
- B \(^{21}{C_8}\)
- C \(^{21}{C_7}\)
- D \(^{30}{C_8}\)
Answer & Solution
Correct Answer
(C) \(^{21}{C_7}\)
Step-by-step Solution
Detailed explanation
\(30\) marks to be alloted to \(8\) question. Each question has to be given \( \geqslant 2\) marks Let questions be \(a,b,c,d,e,f,g,h\) and \(a+b+c+d+e+f+g+h=30\) Let \(a=a_1+2\) so, \({a_1} \geqslant 0\) \(b=a_2+2\) so, \({a_2} \geqslant 0,.........{a_8} \geqslant 0\) So,…
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